I did some storage upgrades on my main workstation and ended up reinstalling as a result.
Ever since, my display configurations get reset every time I reboot. Sometimes they reset while I am using the system.
By “reset”, I mean the order of the displays change, the primary display changes and the refresh rate changes back to defaults.
Anyone have any ideas? I thought I remembered seeing someone else with this issue but I couldn’t find it when I searched.
Are you using KDE?
Maybe something related to this?
Did you re-use any config from the old setup in /etc/X11/xorg.conf.d/ or other?
Have you kept a backup of /etc/*?
How did you change the defaults? On system? On user (KDE)?
It sounds like kernel related, but only logs could give a clear view. 
You may post some info/logs, if/when you feel like it 
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No, nothing was re-used.
Yes.
I changed the settings from in System Settings. I didn’t change the defaults.
The only interesting thing I see in the logs I see this:
kded5[3503]: Settings schema 'org.gnome.desktop.interface' is not installed
That is always followed by a core dump of kded5.
I also noticed I was using the modesetting driver so I installed the correct X11 driver. We will need to wait for a reboot to see if that is the issue.
Then, changing Primary and refresh rate is meant for Plasma, or also system (boot, sddm)?
Yes, just for plasma.
Standard workaround is to delete kscreen folder in ~/.local/share and ~/.config.
Else, go for clearing ~/.cache.
After a reboot it seems to be working. Unfortunately since I was in the middle of getting everything setup I am not sure exactly what fixed it but since I didn’t change much in the way of config, it is most likely all the proper video drivers being installed.
Thanks for the help everyone.
I get a similar bug, but very inconsistently. When my monitors turn off due to being idle, or when I reboot, there is a small, about 1%, chance that my wallpaper will reset to the default one, and sometimes the two displays get switched. I notice it at least once a month, but I don’t know how to reproduce it myself.
Unfortunatelly, Plasma (AI) thinks that it is smart enough to auto configure displays, listening to hardware changes.
These issues point to this, that one or more monitor are supposed to be disconnected, so Plasma uses the default configuration for a new monitor, creating a new hash as a MonitorID. Some time ago, it was using ~/.cache/ related data, which I don’t know if it still uses them, or how.
Most frequent issues are usually with DP/DisplayPort connected H/W, which seem to produce some behavior very close to being disconnected, when going for PM sleep.
In such or similar cases, a relevant workaround that would either don’t let them sleep, or block Plasma from auto-configuring, might help, but I have not tried any, when using Plasma. Instead I had chosen to switch to bspwm, to have complete control of my DE .
Standard control freak situation! 