The screen on your Android device switches between portrait and landscape mode in response to the way you hold the device when you run certain apps. Some devices, such as Google Nexus devices, the home screen switches screen orientation automatically by default.
If you don’t want the screen to switch between portrait and landscape when you move the device, you can lock the screen orientation. To do this, swipe down from the right side of the top panel.
Hold the device in the orientation in which you want it locked. On the drop-down menu, touch the “Auto Rotate” button.
The “Auto Rotate” button becomes the “Rotation Locked” button. Touch a blank spot on the desktop or touch the device’s Back button to close the drop-down menu.
Now when you move the device, the screen orientation stays the way you locked it. When locking the screen orientation, remember to hold the device in the orientation in which you want it locked.