Manage Pages

Are you talking about the Admin Panels?

They should be no bigger than any other text on your administration panels. Make sure you haven’t changed the text size in your browser. From the browser menu, choose View > Text Size and select normal.

There are other Admin Panel Themes that you can choose if you don’t like the look of the ones you have. See:

http://codex.wordpress.org/Using_Themes/Theme_List#Admin_Themes

You can manually go in and change the fonts in your Admin Panels, but it may change the fonts for ALL your panels. Try a different theme instead first, because if you change it, next time you upgrade WordPress, you will have to change it again.