Samsung Galaxy Tab A (8.0) - Adjust Brightness Settings
From a Home screen, swipe up or down from the center of the display to access the apps screen.
Navigate: Settings > Display (left pane).
From the Brightness section (in the right pane), slide the blue bar left or right to adjust brightness.
To increase brightness for 15 minutes for better outdoor viewing, tap the Outdoor mode switch to turn this setting on o desactivar .