Select Settings > Display.

Brightness Level

Sets the display brightness level on your device.

Theme

Allows you to select day or night color mode. If you select the Automatic option, the device automatically switches to day or night colors based on the time of day.

Wallpaper

Sets the wallpaper background on your device.

Sleep

Allows you to set the amount of idle time before your device enters sleep mode while using battery power.

Daydream

Enables or disables the daydream screen saver.

Font size

Increases or decreases the font size on your device.

Cast

Enables you to show the contents of the device screen on a compatible external display wirelessly.