To create cross-staff notation with the Cross-staff Plug-in.
Select the measure region including the notes you want to move to a different staff. See Selecting music.
Hold down SHIFT+ ALT and press the DOWN ARROW key to move notes down a staff, or the UP ARROW key to move the notes up a staff. For additional control over cross-staff notes, use the Note Mover tool (as described below). See also Cross-staff plug-in.