Because for me it shows both watched as well as unwatched shows and movies, which makes no sense tbh. For example, I have seen Watchmen and also marked it as seen.
The top row shows the video you are watching! Videos without watch history show the first resource added
Welcome to the forum!
The users guide for lists and favorites and how to customize them will help get things set up like you want.
Also the “Up Next” setting can be used to select what you see on the top row.
Watchmen is already marked as watched, but still shows up.
Did you stop the movie before the credits finished? If so, you may have stopped a bit before the fully watched threshold was reached. What happens if you go to that movie pre-play screen and click on mark as watched?
What do you have the settings for the “Up Next” options?