By rotating your device you can change the screen orientation from portrait to landscape. An example of landscape mode is displayed below:
If the screen does not rotate if you rotate your device, you should check the Android ‘Control panel’. Swipe down from the top-right corner of your screen to open control panel. Swipe down on the panel to see all options. Tap the automatic rotation button if it is disabled. Next to that you should disable the Topo GPS setting Display Orientation > Lock.
If you do not want the screen to rotate if you rotate your device, you should enable the Topo GPS Display Orientation > Lock.