If you tap on an unassigned Shortcut button, the smartpen prompts you to assign a command to the shortcut.
The Shortcut button number 1 is assigned by default to syncing. You can re-assign it, and assign the other Shortcut buttons. See Shortcut Buttons.
If you accidentally tap on an unassigned Shortcut button and do not wish to set it, tap the Home button or any unwritten area of Livescribe Dot Paper.