In wood or plastic, self threading screws will become loose if they recut
new threads each time you put a screw back in after working on some part.
To make the screw hole last longer, when you first start the screw, turn it
counter-clockwise with light pressure. It will make a slight pop inwards
when you align with the old threads. Stop the counter-clockwise rotation
and rotate clockwise from this point and the screw will follow the original
threads that were cut. This will make the hole stay tight much longer.