Jo Ann, but I was referring me to the avatar in this path:
wp-content/themes/symbiostock_ptbr/img/generic-user.jpg
So, I had manually overwrite the file generic-user.jpg with my own avatar. Not sure if it was the correct way, but worked. :0)
In the network form there is just the site avatar 32px or logo avatar 128px (Squared), and not author avatar (generic-user.jpg).
Thanks for the links anyway. ;0)