The app can be protected with a PIN code. To set up the PIN code, tap the i button at the bottom right of the app.
Select Setup PIN Lock. You will now see the PIN code menu where you enter the PIN code you wish to have. Switch on Enable lock when starting to activate the PIN code lock.
If you forget the PIN code, you will have to uninstall the app from you phone/tablet and re-install it again. You will then need to add all cameras again. The settings in the cameras are stored within the camera and will not be affected by this.