My glasses have screws at the temples…like most glasses.  My sister-in-law works in an Optometrist office and she gave me a great hint for those screws that work their way out.

She said do not use super glue because if the lens pops out, you cannot get the frames open to replace the lens.  Instead, put clear finger nail polish on the tiny screw and screw it down into the hole.  It will dry and hold the screw in and then if you need to open the frame to put the lens back in, you just use finger nail polish remover on the screw area.