Just a note that I upsized the avatars a little bit. The default was 65 x 65 pixels. I had increased that some originally, but I realized they can be wider without making the posts bigger. So I increased the max size to 100 x 70 pixels.
If the picture source is external (i.e. hosted on another site), then it probably adjusted automatically.
If you uploaded the picture, you'll need to upload a bigger pic to take advantage of the new size.