I would like to say first off I am a drywaller not a painter. but i’m helping some family paint right now. i’m using Behr ceiling paint and a 3/8 nap 18inch on smooth ceilings.

i’m painting/rolling over what seems to be gloss or maybe semi gloss ceiling paint. i’ve put 4 coats on just to cover the green ceiling in one bedroom. and 4 coats on a blue ceiling in a bedroom. why is it taking so many coats?? paint quality? do i need a 1/2 nap? or is that just what i get trying to paint a dark color white again? should i switch brands ? even my trim cost was taking 3-4 coats. any suggestions would be great! (i did not prime the ceilings)