AFAIK, they are hardcoded inside Poserand not really accessible to change. Many have complained but I haven't seen a solution so far. If you're on Windows, you can use the Microsoft Magnifier accessory. It's a bit of a hassle to use alll the time but if you're really having trouble reading the dials, it works. I'm sure there are probably freeware/shareware magnifier utilities out there that may be nicer as well and probably Mac equivalents.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken