ok install widget logic
https://wordpress.org/plugins/widget-logic/
this adds a box to each widget in a sidebar
so work out which sidebar is showing in your bbpress pages and for each widget in that sidebar into that box put
is_bbpress() if you want it to appear in forum pages
!is_bbpres() is you don’t want it to appear in forum pages (but do want it on other pages where that sidebar appears
and leave blank if you want tit to appear on both forum and other pages