From a Home screen, swipe up or down from the center of the display to access the apps screen. These instructions only apply to Standard mode and the default Home screen layout.
Navigate: Settings > Display.
From the Brightness section, do one of the following:
To adjust automatically, ensure Auto brightness is on . Brightness is optimized under varying lighting conditions.
To adjust manually, ensure Auto brightness is off then slide the blue bar left or right to adjust the amount of brightness.