Go to My Settings and then Edit Profile, it should be an option in there, but I hink the server updates every 5 or 15 minutes, so you may have to wait for a bit for the option to appear And thats not dumb, took me a while to find it first time too What are you gunna put in it?
Yes, permissions are updated every 15 minutes so it can take up to 15 minutes between getting a specific post count and having the extras that go with it. This applies to the custom title at 500 posts and also the chatroom and homepage access at 10 posts.