Stop service:
$ sudo systemctl stop transmission
Change settings from command-line, for example, to configure the downloads directory or port:
$ nano /home/osmc/.config/transmission-daemon/settings.json
Change required values as:
"download-dir": "/media/Elements/Downloads",
"peer-port": 51413,
"script-torrent-done-enabled": true,
"script-torrent-done-filename": "/home/osmc/bin/torrent-done.sh",
"speed-limit-up": 1000,
"speed-limit-up-enabled": true,
Start service:
$ sudo systemctl start transmission