Some programs control their own system fonts. You may not be able to. I've found this problem in Microsoft Websites... they build the ability to adjust text size into the web browser, then they suppress the feature on their own website! How unfriendly can you get?
In this situation, the only recourse I've had is to temporarily change my display settings temporarily, lowering the overall resolution, then switching back when I'm done with those sites.
LAST IDEA: Use a magnifying utility to read:
Lens - Magnifying Glass - Free software downloads and reviews - CNET Download.com