[Milhouse]

I think guisettings.xml gets overwritten from some settings cache as part of a shutdown or reboot from the menu.

There may be another (better) way to preserve an edited guisettings.xml through a reboot, but the reboot command in a terminal session does the job.

If you want to edit guisettings.xml without xbmc overwriting your changes simply shut down xbmc first with "systemctl stop xbmc.service", then edit guisettings.xml, then finally start xbmc with "systemctl stop xbmc.service".