It's not the font size. The artists and song titles in my library are so small I have a hard time reading them

Oh .. did you even try? lol I did.

you go to the themes folder which is located in

C: Drive >
Documents and settings >
(user name) >
Application data >
Limewire >
themes >

then select the name of the theme that you are using (select the folder not the lwtp. file!)

then scroll down to the text file
open it

select "user text font"
change the "size" from (whatever size) to a larger one