If you're picking from one of our existing avatars, after you choose it, you need to make sure you hit the "Save" button all the way at the very bottom of the screen. It's easy to miss.

If you're trying to upload your own personal avatar, it has to meet these requirements or it won't upload:

Once you've browsed to the file on your computer and uploaded it successfully, again you need to click the "Save" button at the bottom of that screen.

Let me know if that helps...