Thanks zybex
May have got it sorted, what a game
Set up as you suggested, but the "Set full screen monitor #2" would not let me go higher than "desktop settings" which stuck at 1080. and playing in Theatre View showed 1600 x 900 again on the wrong size OSD (where this number comes from I don't have a clue) see pictures
So I set the TV as the default monitor and went through your suggestions again and it seems to work, even the HDR passthrough, and OSD is right size.
And no dropped/repeated frames after pressing ctrl r to reset, I guess performance "avg/peak ms" is within limits
Obviously the desktop in now on my TV and the laptop below is blank, but MC opens in the laptop screen and I can drag its short cut down if needs be
Do others have to go through this or just (Senior) me?
Thanks again
Steve