HTC One M8 for Windows - Manual (Page 180)

Changing sound settings
Setting your phone to silent mode
When you keep pressing the VOLUME DOWN button until the volume level
reaches zero, this makes your phone vibrate only. To be able to switch
your phone to silent mode using the VOLUME DOWN button, you need to
turn vibrate off in the settings.
1. Swipe down from the top edge of the screen with one finger.
2. Tap All settings > ringtones+sounds.
3. Tap the Vibrate On/Off switch to turn vibrate off.
Choosing notification sounds
Choose different sounds for different types of notifications. You can use
different sounds for incoming text or chat messages, voicemail, and email
notifications.
1. Swipe down from the top edge of the screen with one finger.
2. Tap All settings > ringtones+sounds.
3. Tap the box for each notification type, and then choose a sound to
assign to it. You can also turn on or off sounds for reminders, key
press, camera shutter, and more.
180 Settings