Doesnt have chat settings
To toggle this go to Messages app > settings > chat settings > and click either on or off on "Share typing info atop indications". This function is Samsung's equivalent of read receipts on apple and much like it, it only works with other Samsung phones.
Its also possible that someone else got added in, and those symptoms sound like a group text?
I was able to find how to turn my phone on to safe mode. Should I enable it or..? I'm just trying to understand what that would have to do with my texts going through as chat, and no ability to change it back.