Display Settings
Select Setup > Display.
Backlight Timeout: Sets the length of time before the backlight turns off.
Orientation Lock: Locks the screen orientation in portrait or landscape mode, or allows the screen to change orientation automatically based on the device orientation.
Auto Lock Screen: Sets the screen to lock automatically.
Battery Save: Saves the battery power and prolongs the battery life by turning off the screen when the backlight times out (Turning On Battery Save Mode).
Appearance: Sets the displayed accent colors for day and night (Appearance Settings).
You can use battery save mode to prolong the battery life.
Select Setup > Display > Battery Save > On.
In battery save mode, the screen shuts off when the backlight times out. You can select 
to turn on the screen, and you can double tap to view the status page.
Select Setup > Display > Appearance.
Mode: Sets a light background, a dark background, or automatically switches between the two based on the sunrise and sunset time for your current location.
Day Color: Sets the color for the selections made when in day mode.
Night Color: Sets the color for the selections made when in night mode.
Landscape Controls: Places the controls on the left or right side of the screen when in landscape mode.