The issue @PitaJ linked and this commit https://github.com/NodeBB/NodeBB/commit/6e5de39ba05984a2791e01fffdb2a48a8b4924c5 are related to this bug.

You should be able to configure the unread cutoff in the ACP, https://github.com/NodeBB/NodeBB/blob/master/src/topics/unread.js#L50

That was just what I was looking for. Thanks!

I've got two questions concerning notifications. Is it possible to display more notifications in the "notification window"? This seems to be limited to 15? I know that I can see all on the /notifications page but it would be easier to just see more in the notification window. Is there any possibility to display the category of the topics in the notification (either notification window or notification page)? Or should I put a topic for that in feature requests? Thanks for your help.

https://github.com/NodeBB/NodeBB/issues/6350

I did, thanks.