chat icon / avatar ist not displayed – no gravatar used

Hello,

I have installed a plugin “WP User Avatar”. So the users can upload their profile pic and do not have to use gravatar.

In bbp Messages sometimes the src is a gravatar url and only the alt-text is displayed.
In the meneu “Messages” the avatar is not showing in the header but in the chats.

Does anyone know how I can change the source of the avatars?

Tank you very much for your help!
Regards,
Alex