[@casiepa Moderator 10 years, 6 months ago]

Yes, I understood, so you should find your answer in one of the 3 links I provided.

Most probably this ?

Dashboard>forums>all forums and edit each forum
put the banner in the description
then download my plugin
https://wordpress.org/plugins/bbp-style-pack/
and tick item 6 Add Forum Description on the forum display tab

But read the rest too.
Pascal.