How can I disable chat heads? My grandmother has a Motorola Droid Maxx 2 running Android 6.0.1 and she would like to disable chat heads entirely, for text messages and Messenger. A preliminary search through her notification settings, Google, and this site yielded no results. How can she do this?
There should be a menu called "Advanced Features". Tap on that and then you will find something about smart pop-ups. Find the messaging app and disable it from there.

On my Samsung A50: