They just write a new title and it erases the previous one. The idea is to prevent "clickbait" titles. In practice it mostly destroys information. It would be

They just write a new title and it erases the previous one. The idea is to prevent "clickbait" titles. In practice it mostly destroys information. It would be kind of acceptable if it was done immediately after posting, or if there was some kind of time limit. But it can happen at anytime, and sometimes links that have been upvoted for half a day suddenly change titles, which is infuriating.