I bought a new monitor to replace a older VGA monitor connected to my Zotac ZBox computer running 42.2 and KDE. After starting up every thing worked fine until I went to the Desktop Settings-Monitor setup, and chose to try a lower resolution than the automatically selected 1600x900 . At that time I lost the display image. The display however will work under root and also during Boot up, but once the USER part of KDE takes over the image is gone. The new monitor works fine with a VGA cord however.
This morning, acting on a hunch, I hooked up my old monitor with VGA and the new monitor with HDMI cable and I got both working. The old one and the new one both displayed and the mouse would move from one to the other but only one had controls for desktop actions show up. Trying out various setting in the desktop settings such as changing primary display or turning off primary display, and than disconnecting the VGA monitor still resulted in not having a user display if only the HDMI monitor is connected. Obviously there is a problem in a settings file somewhere. Something prevents the HDMI display when only one monitor is connected.
Does anyone have a solution that does not involve losing all my personal preferences or installing a new OS? KDE is Plasma 5.86
Thanks for any assistance