I need help getting my cylinder head aligned properly.

We have successfully reinstalled the head on the one side. But despite several attempts, we cannot get this other side to sit properly. If we get the back on where its supposed to be, then the front lifts off. Vice versa. We have no problem getting the bolts into position and started. We just do not want to damage the head. When removing the heads the heads lifted off without resistance or any force whatsoever