[Bee-Sting]

If anyone could help me with this I would be eternally grateful!

Is there any way to activate Activity Plus to show on forum posts and replies and not limit Activity Plus on walls, only?

[shanebp]

You should ask the creators of the Activity Plus plugin.

You should be aware that forums and activity are different components.
And that forums has its own support site: https://bbpress.org/forums/
There may be a plugin re images in forums.