I know this sounds daft, but for the life of me I can't cancel the pics of three seats on small centre screen. Sure it's to do with rear seat belts, but if no one in rear, the symbol is still there. Grateful for any help. Thanks.

They are indeed rear seatbelt indicators. SWMBO and I tested this last week in our Fabia. When she sat in the back and fastened the belt it showed on the Maxidot display.

IIRC they disappear after a few minutes if nobody gets in the back. Not sure why yours remain displayed though.

As above. I think they clear off screen above 10mph