dissapear

The article snippet length settings are disappeared in preview mode in my ACP. Why? But it works in the expanded view. Is it normal? How I can control otherwise?

I'm not sure if this is the correct title for this. The idea is to remove alerts when an action is undone. Or after opening a notification, the same notification in all other devices should get cleaned out. For instance, when a user creates a post, followers get notifications. Then again, the...