Having not used VLC for some weeks, i reinstalled on a new desktop system. It still misbehaves, opening too large or partially off-screen!
My system is a Win10 desktop with two GPUs and three monitors, two of the monitors are mirrored. The third is my main one. However, this was not the setup previously when I first posted so can't be blamed I don't think.
I have played with the many settings in VLC but don't really know what I'm doing.
AFAIK there is no solution for this problem. It has been there for a long time.
Frankly, I am not aware of any setting that will avoid this behaviour.
Today I launched the
portable version, vlc-3.0.11-win32, on a Windows system that did
not have VLC installed.
It started off-screen right from the start.
After changing the Windows size and restarting, it will use the last use Windows size. That is fine.
However, loading whatever a high quality .mp4 or .mkv, VLC will automatically resize the window again.
Disabling 'All Settings'>'Video'>'Video Auto Scaling' did not help.
LATER: matter solved... see later posts.