Galaxy S6 sound resetting itself

[AC Question]

I set my Galaxy S6 to silent or vibrate and shortly after it resets itself to ring. If I want to make sure my phone doesn't ring at work I have to turn it completely off. I first noticed this about a week after installing Android 6.0.1. How can I make it stop?

 

[the tall guy]

Hi, do you have 'Do not Disturb' enabled or anything like that? what process do you follow to put your device on silent?