HTC One M8 for Windows - Manual (Page 179)

Changing display settings
Adjusting the screen brightness manually
1. Swipe down from the top edge of the screen with one finger.
2. Tap All settings > brightness.
3. Tap the Automatically adjust On/Off switch to turn it off.
4. Select the Level of brightness to use.
Setting the time delay before the screen turns off
After a period of inactivity, the screen turns off automatically to save
battery power. You can set the idle time before the screen turns off.
1. Swipe down from the top edge of the screen with one finger.
2. Tap All settings > lock screen.
3. Tap Screen times out after, and then select the time length that you
want.
Settings 179