Change group avatar in Buddypress from Gravatar?

I didn't put in a custom image for the first group that everyone currently belongs to, but now I'll be using the groups feature and want to be able to customzie that avatar.

Trouble is... it's pointing to gravatar right now, so there isn't an image that I can just swap out. And for the life of me, I can't figure out how to change the picture away from it!

How do you change the avatar for an existing group in Buddypress if it's currently set to Gravatar?

Any help would be appreciated.

Thanks,
Steve