best thing to do is take your picture and put it in some kind of image editor such as Pain, or I use PhotoScape which is free. You will want a background that is 96x96 pixles. Create the background, then lay your image over it making sure that all of it is in the box.

What is happening is the software is using the shorter of teh two sides and cutting the longer side down.

Oh, and when you save the image, save it as a .jpg and not .png. XF seems to like jpg a little better.

 

Nope lol. And the staff is not immune from it either. Look at mine. I just have not modified it yet.

 

I just changed my avatar. If you are wondering, the original size of mine was 555x309. Now, it's 555x555

 

The Xenforo software is very nice because you don't have to worry about large pictures it will size them down automatically. The downside is it can be too smart for its own good and crops any image which isn't a square!