Al,
While you can't change the font size in the interface, you can do the following:
Follow the instructions on this page:
http://kmeleon.sourceforge.net/docs/custompref.php
and add the preferences listed on this page for font size:
http://kmeleon.sourceforge.net/docs/mozpref.php
Tthe defaults are 16 and 13 so adjust accordingly.
Andrew