@cassolotl That's a !GNUsocial question, not related to the !qvitter interface :)
I don't know what you mean with "authorise Twitter". If you're interested in posting from your quitter.se account _to_ Twitter, then there is a separate Twitter tab in the settings for that, on instances where it's enabled. (The # connections page is for doing the same, authorising third party apps/services, but with the quitter.se account)