How to Change your Font in wow
1) Create a folder named "Fonts" in your wow directory
2) For your chat windows and button text, copy your desired font to your WoW>Fonts folder, and rename the font "ARIALN.ttf"
3) For everything else, copy your desired font to your WoW>Fonts folder, and rename the font "FRIZQT__.ttf" notice the double _
thats all just relog wow now and it should work