This is probably a stupid question but all of a sudden all of the posts have "retweet" where "quote" used to be. If I click on it it takes me to a Twitter sign in page. What has happened here - is it a setting. At the moment I can't reply to a post.

Thanks. Problem solved. I noticed it was only on the Politics thread and have discovered it was because the one I was on had just been closed and that on the new one everything is normal!