Hi @stigolsen
What you should try :
(- read http://codex.bbpress.org/amending-bbpress-templates/ )
– create a folder named “bbpress” in your theme’s folder
– create a loop-forums.php file in it
– copy+paste the content linked in loop-forums.php (click the third button just above the first line of code in pastebin.com, then use Ctrl+C to copy)
– upload this new file in its new folder on your server
That should be OK. Be careful when you update your theme, the loop-forums.php may be deleted.