If you’ve upgraded to iOS 11, you may have noticed that the side volume control buttons no longer adjust the ringer volume when you press the up and down keys. Instead, they only adjust the general audio volume.
If you prefer to have the side volume control buttons function the way they did in iOS 10, you can easily make the change. To do this, go to “Settings” then “Sounds & Haptics.”
In the “Sounds & Haptics” screen, go down to “Ringer and Alerts.”
You will notice a new toggle switch labeled “Change with Buttons.”
Slide the toggle switch to the on position (green) and the side volume control buttons will once again allow you to adjust the ringer volume like they did in iOS 10. In addition, when you are playing audio or video, those side control buttons will automatically change from controlling the ringer volume to the general audio volume so that you can adjust the sound as you did in iOS 10.
If you prefer the default setting in iOS 11, you can always change the ringer volume by using the volume slider in the “Ringer and Alerts” section.