Note: I use PHPStorm a particular way and so some of the standard settings make no sense at all. I am making note of some of the things that I have to remember about PHPStorm so I don't go crazy.
Editor > General > Editor Tabs
- Set tab limit to 1
This is so that when you close a window, it actually closes the window. Otherwise you have to close the window once for every file that you ever opened in that window.