Hi,
I have a dual monitor configuration, which I used to keep in `extension' mode. Once I updated from KDE Plasma 5.2 to 5.3, after the start up the monitors are mirrored. I am able to change this setting through the display manager and restore the monitors in "extension", though this setting seems volatile and after each reboot the monitors are back to the mirroring mode. Did anybody experiece this issue?

thanks,
s.fox

I have a similar problem. The second monitor works until download Splash-Scream. The monitor is switched off. It is only activated after configuration.
I find file /home/antik/.kde/share/config/systemsettingsrc but do not know what the name of the section should be there.