SUMMARY I changed global scale in display configuration to 125%. Rebooted. After a test I changed it back to 100%. Rebooted. Then the problems occured. SDDM login screen and KDE apps did not change scale back to 100%. After googling I found out that I had to froce fonts DPI size to 96 and add following lines to /etc/sddm.conf [XDisplay] ServerArguments=-dpi 96 to make things as they were. STEPS TO REPRODUCE 1. Display settings > Change global scale to 125% 2. Press APPLY 3. REBOOT 4. Login 5. Display settings > Change global scale to 100% 6. Press APPLY 7. REBOOT OBSERVED RESULT everything is still scaled up! EXPECTED RESULT default as before 125% global scale shange SOFTWARE/OS VERSIONS Operating System: KDE neon 5.22 KDE Plasma Version: 5.22.4 KDE Frameworks Version: 5.84.0 Qt Version: 5.15.3 Kernel Version: 5.11.0-25-generic (64-bit) Graphics Platform: X11 Processors: 12 × Intel® Core™ i7-8086K CPU @ 4.00GHz Memory: 31,3 GiB of RAM Graphics Processor: GeForce GTX 1060 3GB/PCIe/SSE2 ADDITIONAL INFO: I've got 3 monitors setup with 2 of them 2560x1600 resolution and 1 monitor with 2560x1440 resolution
Had you run system settings -> login screen -> sync settings? If you run that again does that resolve it?
I can confirm. Removing [XDisplay] ServerArguments=-dpi 96 from sddm.conf and system settings -> login screen -> sync settings did help to reset SDDM layout.
I think the best thing would be to avoid syncing that setting, as it has a knock on effect on the dekstop and instead manually insert a QT_SCALE_FACTOR into the env of the greeter.
No objection to that, as long as it can read the correct scale factor before the user session has started.