Got it. Thanks. That has given me 1 big step ahead and another big question though.
1 - I can go full screen & I can change the resolution too to 1080 from 720 and it looks much better. BUT
2 - I can’t specify that I want Zwift to open on the 2nd screen (the TV) which I now need to find a way to do. Whilst in window’d mode I could just drag to the 2nd screen and maximise, but this left the title bar at the top.
Edit - I’ve researched that WIN + SH + Right Arrow / Left Arrow moves maximised Zwift between monitors instantly.
This is 90% of the way there. However if you type anything on the PC then Zwift is instantly minimised on both monitors. Ideally I can solve this, then I’ll be able to use the PC with Zwift running.