If everything has changed size, than I think BeardedBruce is on the right track...you do have to be on the desktop rather than in some other application (like, for example, this chat box) for it to work. When you get to settings, look for the slider in the bottom left corner of the box, click and hold it, and put it where you like it. Personally, I like 1024x768...that gives me a text size about the same as a 12-point font at the distance I sit from the screen.