The Samsung Galaxy Tab flips the screen orientation to landscape or portrait based on how you are holding the device. If you’re moving around a lot and don’t want the screen orientation to change, you can enable this setting.
1. From a home screen, tap and hold the notification bar at the top of the screen.
2. Continue to hold the bar and slide it down.
3. Now you can tap Orientation lock. When enabled (green indicator lit), the screen will lock in the position you have it. When disabled, the screen will flip between portrait and landscape views.