The online instructions mention a Font option in the Options menu. I can't find it. The current display font is too small for me to comfortably read. I'm using version 14.00.0.1003.
Some configuration settings moved in UltraCompare version 14.00 in comparison to previous version 8.50 because of themes feature.
Open View - Themes - Manage Themes and you see in total 3 Set font buttons on the 2 tabs.