Laying flat

So it seems my baby doesn’t like to lay flat on his back. Every time we lay him in his bed it seems he just can’t get comfortable, he’s constantly moving and wiggling around and tends to not sleep long. But put him on our chest with him laying on his stomach he is so comfty doesn’t move at all and can sleep for hours like that. I’m not sure what to do about this because they say lay them on their back, which I do but he just doesn’t seem to like it. When he’s in his bed he might last a hour without movement/ sounds (grunts really bad when he moves) he will also open his eyes several times and try to go back to sleep but May take him a while and sometimes ends up crying because he can’t get comfortable. Does anyone’s else baby not like to lay flat on their back? My husband, me and our daughter are all stomach sleepers and it seems our son will be to, but right he can’t so idk how to help him sleep better