Yeah, bogard mentioned its possible to re-arrange them, but... i have no idea how.
For the avatars, you must pay attention to this
It crops avatars depending on it and as mentioned for it to properly work, you'd need an avy of at least 400 x 400 pixel and preferably the height being bigger than the width.
After that, as mentioned before you can readjust them depending on your liking, by moving the place i indicated with the arrow, while using your mouse to move and shift it depending on your liking, but if your avatar is at least 400 x 400 pixel, you'd not even need to do it