In the picture above it looks like they are all huddled away from the heat plate which tells me the heat plate is too hot.I just turned it down. Chicks were all under it. Now they are out of it so I turned it down. Only two settings and they are signified by a white notch (not temp. no.) This is all so nerve wrecking - the heat/no heat thing. I am in SE GA and it is hot as dickens (to me). No central air in this house. I can't imagine them cold, but as a neophyte I am trying to do what I am learning.
I would suggest not stressing about added heat especially since they are inside your unair conditioned house.
You can leave the heat plate in there but I would pull it away from the edge of your setup so nobody gets stuck under it.
Pull it away so they have room to come out from underneath it from all directions.