Force RGB Color on M1 Mac

Force-RGB-Color-on-M1-Mac.md

Force RGB Color on M1 Mac

How to Force RGB Color Output instead of YPbPr on your M1 Apple Silicon Mac for an External Monitor.

This step-by-step video tutorial will guide you through the procedure of forcing RGB color output on your M1 Mac.

Here is the direct link to the video tutorial: https://www.youtube.com/watch?v=Z1EqH3fd0V4

The video also has Closed Captions (Subtitles) that you can enable, to make it easier to follow if needed.

Please note that you're doing any changes on your own risk.

Terminal commands used in the video

Here are each of the Terminal commands mentioned in the tutorial, so that you can just copy and paste them:

open /Library/Preferences

plutil -convert xml1

plutil -convert binary1

plutil -lint

The step-by-step procedure on how to force RGB Color Output on M1 and M2 based Macs with Terminal commands

1. Open Terminal and use this command to make Finder select the displays plist file:
   open -R /Library/Preferences/com.apple.windowserver.displays.plist

2. Drag and drop the com.apple.windowserver.displays.plist file to Desktop manually. Don't use the cp command, as it won't add your current user with writing privileges.

3. Convert the file to XML:
   plutil -convert xml1 ~/Desktop/com.apple.windowserver.displays.plist

4. Open the converted file with the default plain text editor (avoid using the built-in TextEdit app if possible, since it might modify the file and make it unreadable by the system)
   open -t ~/Desktop/com.apple.windowserver.displays.plist
   or
   open -a CotEditor.app ~/Desktop/com.apple.windowserver.displays.plist

5. Copy and paste the missing LinkDesription Key under the current display (check the screenshot below for an example of how it should look like):
   

				<key>LinkDescription</key>
				<dict>
					<key>BitDepth</key>
					<integer>8</integer>
					<key>EOTF</key>
					<integer>0</integer>
					<key>PixelEncoding</key>
					<integer>0</integer>
					<key>Range</key>
					<integer>1</integer>
				</dict>

6. Save the file and then convert it to binary again:
   plutil -convert binary1 ~/Desktop/com.apple.windowserver.displays.plist

7. Check if the plist file is valid:
   plutil -lint ~/Desktop/com.apple.windowserver.displays.plist

8. Open the /Library/Preferences/ folder again:
   open /Library/Preferences/

9. Drag and drop the updated com.apple.windowserver.displays.plist file from Desktop to the Library folder manually. Don't use the cp command, as it won't add your current user with writing privileges.

10. Right Click on the com.apple.windowserver.displays.plist file in the Library folder and click on Get Info

11. Check the boxes for Stationery and Locked.

12. Reboot the Mac.

That's it!

(Alternative) Terminal commands to force RGB Color Output on M1 and M2 based Macs and workaround for losing RGB color after waking up from sleep

1. Open Terminal

2. Paste the following commands to edit the User's displays plist file com.apple.windowserver.displays.[UUID].plist using the built-in PlistBuddy function in macOS:

/usr/libexec/PlistBuddy -c "add DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:BitDepth integer" ~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist
/usr/libexec/PlistBuddy -c "set DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:BitDepth 8" ~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist
/usr/libexec/PlistBuddy -c "add DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:EOTF integer" ~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist
/usr/libexec/PlistBuddy -c "add DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:PixelEncoding integer" ~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist
/usr/libexec/PlistBuddy -c "add DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:Range integer" ~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist

3. Reboot your Mac
   
   

(Workaround) If your Mac loses RGB color after waking up from sleep mode, either Reboot your Mac (recommended) or use this Terminal command to stop the WindowServer and login again (not recommended):

sudo killall -HUP WindowServer

End result

The end result is having your M1 mac output RGB color to your external monitor instead of YPbPr, potentially making the colors more accurate and the text a bit more crisp, even on older 1080p monitors.

Hopefully this tutorial would be useful to someone.

Please feel free to ask in the comment section if you have any questions regarding this procedure.

Background

While doing a lot of testing on how the Dual-Cable workaround makes RGB to work on M1, I've discovered what changes it makes to macOS, and managed to create a more streamlined workaround without the need to use a second cable.

To make things easier, I've created a step-by-step video tutorial of the whole procedure that should force RGB color output on your M1 Mac connected to an external monitor, and works on an HDMI-to-HDMI cable connection.

Credits

Big thanks goes to the amazing community and all their help over the years to solve issues like this:
https://gist.github.com/ejdyksen/8302862
https://gist.github.com/adaugherity/7435890

Useful Sources

Apple Open Source Project Files for Displays and Graphics
https://opensource.apple.com/source/IOKitUser/IOKitUser-1445.60.1/graphics.subproj/IODisplayLib.c
https://opensource.apple.com/source/IOGraphics/IOGraphics-517.17/IOGraphicsFamily/IOFramebuffer.cpp.auto.html

How to Edit and Convert binary plist files
http://hints.macworld.com/article.php?story=20050803111126899
https://apple.stackexchange.com/questions/155393/how-to-beautify-binary-dict-files
https://discussions.apple.com/thread/1768480

How to Edit plist files using defaults and PlistBuddy
https://ss64.com/osx/defaults.html
https://github.com/mathiasbynens/dotfiles/blob/master/.macos

Apps based on this method

@sudowork has created an awesome script written in Phyton that automates the steps and checks for duplicate files.
You can find more info about it here: https://github.com/sudowork/fix_m1_rgb

@dangh has created an alernative script for fishshell.
You can find more info about it here: https://github.com/dangh/force-rgb.fish

@GetVladimir I've also created a Shortcut to Force RGB Color Output using the built-in Shortcuts app.
You can find how to create the Shortcut here: https://gist.github.com/GetVladimir/c89a26df1806001543bef4c8d90cc2f8?permalink_comment_id=4531552#gistcomment-4531552

@entropyconquers has created a script based on this method written in Phyton that automates the steps, makes a backup and checks for duplicate files.
You can find more info about it here: https://github.com/entropyconquers/Force-RGB-Color-on-M1-M2-Mac-Script

Additional notes

Multiple PixelEncoding and Range keys in the same plist file
Note that there might be multiple instances of the PixelEncoding and Range keys in the same file, one for each output of your monitor and for different AirPlay devices. You might need to update the integer on each one to get RGB color output on all displays.

Getting RGB color only before login
There might be multiple duplicate plist files with the same name in different locations.

Make sure that you only have the main modified file in:
/Library/Preferences

Then make a backup and remove duplicate displays plist files from these locations (if any):
~/Library/Preferences
or
/Users/username/Library/Preferences
and
/Users/username/Library/Preferences/ByHost

Please note that you'll need to have administrator privileges in order to modify the file in /Library/Preferences. Thanks goes to @keegandent and @StrategicalIT for pointing this out.

Updates regarding macOS Monterey

USB-C to DisplayPort
From what I've seen, it seems that macOS Monterey 12.0.1 finally outputs RGB color by default on some monitors when using USB-C to DisplayPort cable on M1 Apple Silicone Macs.

You might need to make a backup and delete these 2 files:
/Library/Preferences/com.apple.windowserver.displays.plist
and
/Users/yourname/Library/Preferences/ByHost/com.apple.windowserver.displays.[UDID].plist

Restart your Mac and it should properly output RGB color on the monitor on the next boot.

HDMI to HDMI
The situation with HDMI seems to got a bit more complicated. Now the whole section for the LinkDescription might be missing from the com.apple.windowserver.displays.plist on a clean install and doesn't seem to be recreated when rotating the screen either.

Luckily, the solution still works, but you might need to manually add this whole section in the displays plist file:

					<key>LinkDescription</key>
					<dict>
						<key>BitDepth</key>
						<integer>8</integer>
						<key>EOTF</key>
						<integer>0</integer>
						<key>PixelEncoding</key>
						<integer>0</integer>
						<key>Range</key>
						<integer>1</integer>
					</dict>

The section usually goes right under the CurrentInfo key, and it should look something like this:

This should get your RGB color output working on M1 Mac mini, even when connected with HDMI to HDMI cable.

Multiple monitors when one them is using HDMI to HDMI
Additional thanks goes to @somogyi-ede who tested this with multiple monitors and confirmed that the LinkDescription key needs to be added under each monitor instance in order for all of them to receive RGB color output. Link to the comment

Updates regarding macOS 13 Ventura

USB-C to DisplayPort
The macOS 13 Ventura beta seems to outputs RGB color by default on some monitors when using USB-C to DisplayPort cable on M1 Apple Silicone Macs.

You might need to make a backup and delete these 2 files:
/Library/Preferences/com.apple.windowserver.displays.plist
and
/Users/yourname/Library/Preferences/ByHost/com.apple.windowserver.displays.[UDID].plist

Restart your Mac and it should properly output RGB color on the monitor on the next boot.

HDMI to HDMI
Similar as macOS Monterey, the situation with HDMI on macOS Venturs seems a bit more complicated. Usually the whole section for the LinkDescription might be missing from the com.apple.windowserver.displays.plist on a clean install and doesn't seem to be recreated when rotating the screen either.

Luckily, the solution still works, and you still need to manually add this whole section in the displays plist file:

					<key>LinkDescription</key>
					<dict>
						<key>BitDepth</key>
						<integer>8</integer>
						<key>EOTF</key>
						<integer>0</integer>
						<key>PixelEncoding</key>
						<integer>0</integer>
						<key>Range</key>
						<integer>1</integer>
					</dict>

The section usually goes right under the CurrentInfo key, and it should look something like this:

This should get your RGB color output working on M1 Mac mini, even when connected with HDMI to HDMI cable.

(Optional) Lock the plist file and set it as stationary
After the macOS Ventura 13.3 update, the plist file seems to get overwritten on reboot.

After you make the edits in the file, you can try setting the file /Library/Preferences/com.apple.windowserver.displays.plist as Stationery pad and Locked, so that it doesn't get overwritten on every reboot

To do this, right click on the plist file, click on Get Info and check the boxes next to Stationery pad and Locked

This requires further testing and might cause some issues, like not being able to remember new resolutions or display settings. Please note that you're making any changes at your own risk.

Updates regarding macOS 14 Sonoma Beta

USB-C to DisplayPort
The macOS 14 Sonoma seems to outputs RGB color by default when using USB-C to DisplayPort cable.

HDMI to HDMI
The macOS 14 Sonoma seems to outputs YCbCr color by default when using HDMI to HDMI cable.

• Forcing RGB Color Output still seems to work with the original procedure of modifying the plist files

• Modifying the display plist files still works with the alternative version

• After the plist files are modified, putting the Mac to sleep and waking it, it seem to keep the RGB Color output (this seems to be fixed at least on a M1 Mac mini)

If you have any additional questions, please feel free to contact me.

@DeepSubMicronMusic thank you for the update and for the details.

Yes, the alternative method modifies the ByHost display plist file, same as you've suggested: https://gist.github.com/GetVladimir/c89a26df1806001543bef4c8d90cc2f8#alternative-terminal-commands-to-force-rgb-color-output-on-m1-and-m2-based-macs-and-workaround-for-losing-rgb-color-after-waking-up-from-sleep

Losing the RGB color output when waking from sleep was a bug in macOS, and it seems to be fixed in macOS Sonoma Beta

It seems that when RGB output is lost after waking up from sleep it could be restored without restarting the Mac. Manual Log Out is enough to get back the RGB

@dainiusm07 yes, you're right. As long as the ByHost display plist file is modified, it should be re-read on login again.

It should technically be read on wake from sleep, but there seems to be a bug in the later versions of Ventura.

In macOS Sonoma beta, the waking up from sleep seems to be fixed already

I managed to resolve RGB loss on wake up bug by accident on my macbook. For folks using macbooks:

1. Unplug your monitor
2. Restart macos
3. Login
4. Plug your monitor
5. Put macbook to sleep manually & verify that after waking it up RGB is in place

I'm on Macbook Pro M1 with Ventura 13.4.1 (c), plugged via HDMI-HDMI. Also I have edited both plist files in /Library/Preferences and in $HOME/Library/Preferences/ByHost and both files are configured to support RGB on both variants (macbook screen + external monitor & only external monitor)

@dainiusm07 thank you for the details and for the step-by-step guide for the solution.

Let's see if other users can replicate it too.

I'm currently on the Sonoma beta, and it seems to work by default

I can confirm that the procedure from @dainiusm07 worked on my M2 14 mackbook pro too.

@zdenek-jonas thank you so much for checking this and for the confirmation

Unfortunately, the next day to wake up the PC it's flipped again. I am going to try Sonoma Beta

@zdenek-jonas Have you edited both files in /Library/Preferences and $HOME/Library/Preferences/ByHost ? Make sure that your external monitor refresh rate is set to the same value on all variants of monitors combinations & it is the same in both files. Different refresh rates causes external monitor to flash on closing/opening macbook screen and I guess it could cause some kind of issues

@zdenek-jonas Have you edited both files in /Library/Preferences and $HOME/Library/Preferences/ByHost ? Make sure that your external monitor refresh rate is set to the same value on all variants of monitors combinations & it is the same in both files. Different refresh rates causes external monitor to flash on closing/opening macbook screen and I guess it could cause some kind of issues

I have already installed Sonoma Beta. Now it stands RGB. Before that everything worked fine until I closed the laptop once, connected to the monitor. Since then, I've tried absolutely everything but it never worked like it used to. Let's see now.

If anyone willing to pay for an easier solution, buy BetterDisplay app and follow this instruction. There're some great improvement over the plist manipulation method:

• The EDID get re-applied when you turn the monitor on/off automatically, so you don't have to restart your Mac.
• If some other apps mess up your display (Dota 2 in my case), it won't anymore because the display now has a fixed config. Even if it does, you can just re-apply the EDID manually.

This method doesn't work on my M1 MacBook (Monterey). The lines of code to be changed didn't exist in my displays plist file, so I just added them. What I found confusing was that my plist file seemed to contain much more code than Vladimirs. It contains around 650 lines of code with a repeating structure of "Current Info", "Rotation" and "UnmirrorInfo". I inserted the additional code just below the first "Current Info" block, exactly as in Vladimirs screenshot.

I have a Dell U2720Q monitor connected via USB-C. It seems that whenever I first launch the MacBook and then switch on the monitor, the color is set to YPbPr. If I want RGB color I need to reset the monitor to RGB (which results in a pink-green display), then unplug the USB-C cable and plug it in again. Modifying the displays plist file hasn't changed this behavior. I also tried deleting both plist files (including the on in the ByHost folder) and then modifying the one that has been newly created.

@BermudaBen thank you for your comment.

Please check in your monitor setting for an option where you can choose between "High Data Speed" and "High Resolution" and set it to "High Resolution".

If that doesn't work or if you need the faster data on the USB ports of the monitor, please connect the M1 MacBook to the Dell U2720Q with USB-C to DisplayPort cable instead

@GetVladimir Thank you for your reply. The monitor is set to "High Resolution". As for the connection: This would mean I won't be able to charge the MacBook from the Dell monitor, right? Why would it make a difference to use the monitors DP port instead of the UBS-C port? The video signal is DP in both cases. And: Do you know if this is a Dell-specific issue?

@BermudaBen not a problem, thank you for the reply.

When you mentioned that you have over 650 lines of repeating instances of Current Info in the plist file, this usually points to having a dock in the middle of the connection.

It seems that the USB-C to USB-C connection is considered as connected through a dock inside the monitor and then being converted.

The M1 MacBook doesn't seem to see it same as having an actual USB-C to DisplayPort connection.

This might depend on what type of conversion happens in the monitor and it's not isolated to only Dell monitors.

After numerous attempts without success, I finally managed to succeed. I will record what I tried.

[1] I attempted to edit /Library/Preferences/com.apple.windowserver.displays.plist. This method involved changing the refresh rate and other display settings, but it failed.

[2] Next, I tried alternative method, but I couldn't find com.apple.windowserver.displays.[UUID].plist in /Users/username/Library/Preferences/ByHost. However, rotating the screen created a new com.apple.windowserver.displays.[UUID].plist. After executing Terminal commands, I finally achieved RGB!

Thanks to GetVladimir and everyone.

Lastly, I'll provide details about my setup: Mac mini M2, Mac OS 13.4.1 (c), HDMI to HDMI, DELL S2722DC.

@satori-mitora thank so much for your comment and for the detailed steps. Glad to hear that you got RGB color output working

UPDATE: See my latest reply in this gist for complete steps for fixing this problem

If you're stuck with reseting to YPbPr after reboot or sleep here's what worked for me:

1. Take the steps to edit plist in /Library/Preferences
2. Remov plist in ~/Library/Preferences/ByHost
3. Reboot

I removed the plist in ~/Library/Preferences/ByHost in recovery mode because i couldn't log in anymore since i somehow corrupted it .. but i guess it might work in the regular environment as well

okay so that was a short lived fix. here's how i got it to work better now:

• Remove plist in /Library/Preferences
• Remove plist in ~/Library/Preferences/ByHost
• Empty trash
• Reboot
• Connect monitor via HDMI and close the macbook lid
• Copy plist in /Library/Preferences to desktop, convert to xml, add lines below these steps after each <key>CurrentInfo</key><dict>...</dict> entry, convert back to binary, replace original file
• Set the file to Stationary pad and Locked under file info in finder
• Reboot
• Open System Settings > Displays > Rotate your external screen 90deg and back
• Copy plist in ~/Library/Preferences/ByHost to desktop, convert to xml, add lines below these steps after each <key>CurrentInfo</key><dict>...</dict> entry, convert back to binary, replace original file
• Set the file to Stationary pad and Locked under file info in finder
• Reboot

Now every time i start my macbook with the lid closed and connected to the external monitor, the external monitor receives RGB signal upon login.

The login screen for some reason starts in HDR+ mode (lol)

The external monitor for some reason looses RGB mode and switches back to YPbPr mode when disconnecting and reconnecting the HDMI cable though. But i can live with a setup where upon startup things work as expected.

Anyway, waiting for the fall release of the new OS where this nonsense has been fixed..

UPDATE: See my latest reply in this gist for complete steps for fixing this problem

@loucyan thank you for your comment and for the steps on how to fix it

The menu on the LG UltraGear 27GL83A doesn't show the color format, but you can find it in the service menu by doing the following:

1. Turn off the monitor by pressing in the control stick on the bottom
2. Press the control stick left 3 times and right once
3. Turn the monitor back on by pressing in the control stick
4. Open the menu by pressing in the control stick and then pressing it right. This should open the service menu instead of the normal menu
5. Scroll to "DEBUG INFO." using the control stick (pressing it upwards 3 times should loop round to the debug info) and press it right to enter the debug info menu
6. Note the "COLOR FORMAT" displayed

You can exit the debug menu by pressing the control stick left, then exit the service menu by scrolling off the bottom of the menu using the control stick (pressing it downwards twice should do it) and pressing the stick in. Be sure not to accidentally change any values in the service menu!

These steps should hopefully work for other LG monitor models too.

@jackwilsdon that is awesome info! Thank you so much for sharing the detailed steps

@GetVladimir thank you for your work. I couldn't understand why apple put us through this! but thank you and the kind people out their providing this solution. BTW i struggle a bit, until i read about the byHost folder. I delete all the com.apple.windowserver.* files and now my mac m1 behaves.

@ioctlsg Thank you so much for your comment and I'm glad to hear that you got RGB color output working

Anyway, waiting for the fall release of the new OS where this nonsense has been fixed..

Wait, they fixed it? Do you have a source talking about this?

Anyway, waiting for the fall release of the new OS where this nonsense has been fixed..

Wait, they fixed it? Do you have a source talking about this?

@vittau under Sonoma you still have to do the configuration manually, but the wake from sleep and unplugging the external monitor and plugging back in works as expected now as the external monitor retains RGB signal

Here's the steps for Sonoma. Do exactly what it says here, or you will end up with a partially working setup. To my findings all the rebooting is necessary to also capture the login screen configuration.

1. Unplug external display, use only your laptop display for now
2. We want to start with a clean configuration, so delete the two com.apple.windowserver.* plists under /Library/Preferences and ~/Library/Preferences/ByHost
3. Reboot
4. Now we want macOS to set up all configurations that will naturally occur when using our setup. Open System Preferences and set your desired resolution scale
5. Reboot
6. Keep your laptop display open and plug in the external display. Open System Preferences and set your desired resolution scale and assign the desired main display where your dock and main windows will appear
7. Reboot
8. Close your laptop display so only the external display is being used. Open System Preferences and set your desired resolution scale
9. Reboot. Then, reboot again
10. Now we have all possible configuration variants set up in both plists. Copy the two com.apple.windowserver.* plists under /Library/Preferences and ~/Library/Preferences/ByHost to your Desktop manually (cp command will not transfer the needed user privileges)
11. Convert both plists on your Desktop to xml format with plutil -convert xml1 ~/Desktop/com.apple.windowserver.*
12. Open both plists in a text editor. We now want to find occurrences of only the external display and add some additional config lines to them. I'm not sure how to identify them properly, but my external display is 60Hz so that's what i used to differentiate from the 120Hz built-in display configs. Add the code at the bottom of this reply to each external display config in both plists. Consult the screenshot provided in the original gist at the top to where exactly it should be placed
13. Save both plists and convert them back to binary with plutil -convert binary1 ~/Desktop/com.apple.windowserver.*
14. Check if the plists are valid with plutil -lint ~/Desktop/com.apple.windowserver.*
15. Manually copy the updated plists back to their respective folders
16. Right click and Get Info on both, and set them to Stationary pad and Locked
17. Reboot and enjoy

<dict>
<key>BitDepth</key>
<integer>8</integer>
<key>EOTF</key>
<integer>0</integer>
<key>PixelEncoding</key>
<integer>0</integer>
<key>Range</key>
<integer>1</integer>
</dict>

@loucyan thank you so much for the detailed steps and explanation

So when Sonoma was released and theoretically Big Sur won't be getting any more updates I finally upgraded to Monterey 12.7 (I always stay a couple versions back for sanity on my main work machine). I had this RGB mode working under Big Sur but Monterey broke it and I can't seem to get it back.

My main monitor is a 27" Dell S2721QS 4K monitor, connected HDMI-to-HDMI directly to my M1 Mac Mini. My second screen is a 27" LG 27LQ635S-PU FHD TV, connected HDMI-to-HDMI through a USB-C Dock. I'm using a Display Override with "DisplayIsTV" set to false to prevent macOS seeing the HDTV as a TV, so I can set it to 1920x1080 instead of 1080p, which vastly improved text legibility on it, but I have no idea if that monitor is actually in RGB color mode or not, I'm assuming it is because it's not blurry anymore, but text quality did slightly degrade after moving to Monterey.

I had my /Library/Preferences/com.apple.windowserver.displays.plist locked when I upgraded and it was still there and locked after Monterey installed, but doesn't seem to actually be doing anything anymore. I've tried deleting the one "windowserver" file I had in ~/Library/Preferences/ByHost/com.apple.windowserver.displays.[UUID].plist and it respawned but still no RGB mode on my Dell monitor. I also tried adding another file to my Displays Overrides for the Dell also with "DisplayIsTV" set to false, but that didn't work either.

As a side note, Monterey also can't seem to remember my monitor arrangement. I have to reorder them every time I reboot.

At this point, the only reason I care about trying to get the Dell back into RGB mode is because it now randomly experiences the flickering and ghosting problem, which I never saw under Big Sur so long as it was in RGB mode.

In addition to two HDMI 2.0 ports the Dell monitor does have a DisplayPort 1.2 on it too, but I don't have any cables, adapters, or docks for it. I haven't seen anyone talking about using an HDMI-to-DisplayPort cable or adapter, or what color mode that defaults to, but I'm assuming it would have to be an active adapter. Unless a USB-C dock with DisplayPort would be a better option, and then plug my LG HDTV into the Mac's HDMI out? I'd really hate to have to buy new hardware to work around what is clearly a software problem.

@kmhcreative thank you for your comment and for the details.

You might want to try modifying the displays plist file in the ByHost too, as it will take precedence over the one in the Library.

Regarding the monitor arrangements, this was issue in Monterey and I'm not sure if it got resolved.

The workaround is to try a different HDMI port on the monitor and see if that helps

I tried using the "alternative" terminal commands shown above to modify the ByHost plist file and on reboot the Dell monitor is still in YPbPr color mode. I'll try the second HDMI port and see if that at least fixes the arrangement problem.

@kmhcreative thank you for the reply. You will have to modify two UUIDs in the plist file, since you have 2 monitors connected. Each one is only applied for one monitor.