The System bar is at the bottom of the screen and it contains quick-launch buttons, for example the Back and Home buttons. You can add up to two extra buttons to this bar to quickly start apps that you often use.
Tip: Some apps have a full screen setting that hides the system bar when the app is open.
To add a quick-launch button for an app, do the following:
Your new quick-launch button is added to the System bar.
To remove a quick-launch button, do the following:
The quick-launch button is removed from the System bar.