booking.com always offers 2 rooms not one.

Annoying problem that I think is just a quirk in the settings.

I have a property with 3 rooms that sleep 4 and 7 rooms that sleep 2. I have all the sleep 2 rooms set as 2 adults no kids and the sleep 4 as 2 adults and 2 kids max. The problem is when I search for 2 adults and 2 kids booking.com will always show 2 rooms that sleep 2 rather than a sleeps 4 room. Obviously this makes it much more expensive.

Any suggestions on set up would be gratefully received.

That is a weird Booking.com quirk. Booking.com does not count kids in room counts.  If you have a sleeps 4 room with 2 adults and 2 kids - that is considered a 2 person room.