@Jarpur Yes, like Simkie said, those privacy settings won’t control who can see your posts within the actual threads on the forum, but you can control who sees your activity stream on your profile page, who can leave your visitor messages on your profile page, etc.
If you don’t want to make these features available to anyone, you could select “subscribers” as your privacy setting, and then not accept any subscriber requests. A subscriber request is sort of like a friend request.