My first problem seems somewhat common, as I get a number of Google results for it, yet I can’t seem to implement the steps in a way that solves the problem. I am trying to just save my monitor configuration on Linux, but every time I log out, it reverts to the default. I have run nvidia-settings as root in order to be able to edit and save the file, but I am not sure what to do from there.
Also, I have 2 GPU’s, one of which supports a third monitor. This GPU is not configured properly, as it is a black screen with an x for a cursor. Let me know what additional information would be helpful, and if you have any fixes.
I think I read one of these threads here where somebody was having a similar issue and one of the DE display configuration apps (like gnome or unity monitor settings) was overriding what was being set by nvidia-settings.
I don’t recall the answer but maybe you can continue your search with the idea that GNOME display settings, etc. could be the culprit.
I think there was a thread here about it. Maybe search the forum here.
For the second problem I think you need to use a BaseMosaic configuration. You’ll want to check your /var/log/Xorg.0.log file to see if such a config is enabled and / or producing any warnings, errors, etc.