Some of the doors in my home will not close and stay closed. You close them and they come back open. What can I do to fix this problem. They are 6-panel hollow core doors.
Are the door latches facing the right way?
The flat side of the latch should be on the opening side of the door.
Otherwise you might need to reposition the striking plate. Check the latch sits square in the plate, and is deep enough into the plate, 5mm should do.