increase avatar size

I am trying to increase the avatar size on the directory from 96 px to twice that – 192 px. I have tried various plugin settings without success. The result is always that the avatar default picture bleeds outside the listing boundaries and those users that have an associated jpeg picture do not show up. Can someone help me choose the plugin settings that would allow me to double the picture size?

By the way, I am using the Avatar Manager plugin that downloads an avatar picture from a local file. The picture is not in the Media Library, nor is it a gravatar picture assigned to multiple web sites.

If there is someway to associate a picture with each user that is not an avatar, but will be displayed with each user in their listing, please let me know.