SUMMARY
KDE does not remember monitor layout/primary settings after using only one screen.

I have the following screen config: laptop screen and an external monitor which is connected via a cable. Sometimes, I use only the external monitor because I have it in the middle of my table, so I turn off the laptop screen by selecting "only external display" in the overlay display menu (windows has something similar, accessed by Meta+P - quick display settings: only one of the two displays, extend, duplicate etc.).

When I want to turn my laptop screen back on, I do the same process, except I select extend to left. However, my config gets broken: the laptop screen suddenly becomes the primary screen and all windows move there. I have tried several options to "fix" the main screen property to the monitor, but with no success.

STEPS TO REPRODUCE
1. Set your external screen as primary
2. Switch KDE display settings to "external screen only" mode
3. Switch display settings back to either "extend to left" or "extend to right"

OBSERVED RESULT
Screen configuration gets broken.

EXPECTED RESULT
Primary screen should remain the same.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: openSUSE Leap 15.2
KDE Plasma Version: 5.18.6
KDE Frameworks Version: 5.71.0
Qt Version: 5.12.7