(using GNOME. Have restricted nVidia drivers installed and working properly. AMD processor)
I've been pretty much been able to solve (or configure, whenever necessary) all the issues that I came across. For a complete newbie like myself, I think that's good enough. However, for this particular issue, I cannot find straightforward solution.
It appears that the GDM cannot save the settings. No matter which themes I choose, and no matter what resolution I set, it always goes back to default. I don't mind the themes much, but sometimes with the resolution it doesn't let me change it back once logged in, forcing me to restart to fix the issue.
I'd rather not remove resolutions from the conf file. I mean, I'm pretty confident I'll be using the one I have for a long time if not forever, but you never know.