A: Any tech should be able to fix this for you quickly and easily.
Or, if you are handy, and don’t mind working on your instrument, an easy fix is to unscrew and remove the strap button, and then insert a piece of wooden toothpick with a dab of Super Glue on it into the hole. Either break off the toothpick or cut it so that it is flush with the surface of the guitar. The screw holding the strap button should now firmly fit into the hole, and should not come loose.
CAUTION: Be sure you know what you are doing before you proceed with working on your guitar’s strap buttons. Those strap buttons hold the guitar up, and if you do not install them correctly, your guitar could fall off its strap and be damaged. The safest bet is always to use an expert technician to work on your guitar.