I don't have the shift yet, but I'm pretty sure you can't. You can change font sizes within many apps like the browser, handcent, k9 email, etc.
Indeed, I found out you can't. And, you are right, you can change fonts within "some" of the apps, but NOT others, that's why I was looking for some global font setting for my older eyes You know, something like changing the DPI setting on your computer monitor and then not having to worry about an app having a font setting, or not. I also found out that one can root the phone and then change the screen density which would indeed be equivalent to the DPI setting, but I am not familiar enough with the process, so I have to figure out if I can live with using reading glasses each time I have to make/receive a call, send a text, etc. or bring it back and opt for an anachronistic crackberry ;-) Pitty, because I think this is a good, powerful phone.
This was the biggest shocker to me when I first switched to the android platform. Even old model dumb phones have a menu option to change the font size. Before you give up on Android, you might want to try one of the larger screen phones like the Evo or Verizon's Droid X . Larger screen makes for larger fonts. I can't read without my reading glasses, but I can manage most tasks on the evo without.
I have been looking around to replace most of the stock apps with ones that have font size control and so far I've been able to find some that will allow me to use the phone and change the font sizes. So far I have switched to Handcent for messaging and K-9 Mail for email and I am having an easier time. Of course, that doesn't help with the home screen, the apps screen, but I can recognize the little icons, so it's not that bad Now, if I could find a Facebook app that lets me change the font size, I think I'd be O.K. with this phone. Between the font size and font color in the Facebook for android app, I can't read it at all :-(
Instead of a Facebook app, I use m.facebook.com - facebook's mobile website. I like it better than the app in general. Some people prefer the facebook site that's tailored for touch screens - touch.facebook.com Because they are viewed in the browser, you can zoom in. Also, the browser has font size settings I think.
