[@netweb Keymaster 10 years, 3 months ago]

All those topics in those forums are “super sticky”

Go to topics dashboard https://example.com/wp-admin/edit.php?post_type=topic

On each of those topics in the list click “Unstick”

Your issue should be fixed now

See https://codex.bbpress.org/getting-started/forum-moderation/common-tasks/#sticking-a-topic for more info