These are accessed by tapping on the settings cogwheel at the top of the screen and selecting 'Advanced' from the left margin.
You can find all the information regarding advanced settings here
You can access your appearance settings by tapping or clicking on the settings cogwheel at the top of the POS screen and selecting 'Appearance' from the left margin.
The ‘Security’ Settings will give you the option to automatically log out of AirPOS after one, five, ten minutes, never or after each transaction.
If you need to reset the device you run the POS on and sign in, for example, to a different account tap on the settings cogwheel at the top of the POS screen. At the bottom of the screen is a red button to reset your device.