2000 XJR; Where is the trunk light switch?
 

I can't seem to find the switch for the trunk light. Also, the trunk lights are easily dislodged. I even found that the previous owner (or maybe it was made this way) used hot glue to try to glue them in. Is there a better way to secure those lights so they don't fall in (or out)?

The switch is built in to the trunk latch mechanism. It often fails, do a search here and you'll find some more info.