This is probably the stupidest question to all of you (I am clueless about this)

but I put up a new doorbell (a nice one I :may" want to keep if I move)

I relocated it to fit in with the door hardware and....

the 2 screws to keep it tight in place-one screws into wood. the other screws into empty space-nada.

so how the heck do I keep the other screw in place so it doesn't fall out?

I tried putting a small piece of wood/lath type-it split. (it's a very small opening but still a hole so no grab)

should I just put glue in the hole to keep the bronze screw from falling out (I can make the other hold the doorbell unit tight against the wall)

I'm assuming glue would make the screw permanent? I don't want to lose this screw.

and each time I take the doorbell off the wall, it is a pain to remount, and the "button" falls out etc. Can I just glue the metal in there and someday ply it out or something like that? just a quick get the darn screw in there. uggg

thanks all :)