I have Kubuntu 20.10 set up on my system as dual boot with Win10 (though I don't think that matters, just FYI).

My system is a desktop PC with 2 monitors. After installation, I set up the dual displays. The PC is not a recent one, it's a ASUS M32 series desktop PC with integrated ATI (AMD) Radeon video. It has an HDMI output and a VGA output.

Here are some characteristics of the monitors:
LG Flatron W1942TQ - 19" diagonal, running 1440x900 (16:10); VGA and DVI inputs
Dell, also 19", but running 1280x1024 (5:4); VGA and DVI inputs

My setup has the VGA output going to the LG which is on the left, and the HDMI output going to the Dell on the right.
After installation I set up the displays so they show up correctly and the mouse can go from one display to the other on the correct side.
I've noticed that during the login screen that the screens are reversed. Some searching around found that others experience the same situation. Once logged in, it's fine. One suggestion, though, was to try switching the cables.

I tried that (so now the HDMI goes to the LG and the VGA goes to the Dell) and what happened was the displays would be misidentified in the Settings page. No amount of changing the settings could make it show the displays correctly. What I mean is when I would get it to identify the monitors, the Dell display had LG showing on the screen and vice versa.

So I switched the cables back which made everything ok except for the login screen. Is there a way to redo the display setup from scratch?
I have Googled for info on this but so many of the posts I find are always from very outdated times so I thought I would reach out to see if anyone can help.

Update: With further use, I note that when I just put the PC to sleep (ie suspend to RAM) the left/right setup is correct and is maintained (which makes sense). Upon further reflection, I don't think this is something anyone will be able to help with, so I will close out the post.