Found under: Settings > Controls > Assign custom gestures
Custom gestures can be added to the screen for Performance or Stage mode.
By default you can pinch to zoom in/out of songs in Performance mode, but you can switch this feature off if required.
Other custom gestures can be double tapping the screen or long pressing the screen. Note that this only applies to the song display area (not the actionbar, menus or page buttons).
The options available for each custom gesture is the same as those available for the page buttons.