I just installed KDENeon. I am setting up dual monitors, and my mouse is stuck in the bottom screen, whilst the settings window is in the other. Windows are positioned correctly in the Display Configuration preview.
When I unplug second monitor, windows all shift to my laptop screen.
When I plug in a third monitor, all displays are connected, and I can move my cursor freely between all three.

I am new to Linux
tia

SOLVED:
Right-click the settings icon in the panel, select "move". It jumps the cursor to the correct window/display.