You can add instruments to a score set, replace an existing instrument with a different one, and change the order of instruments.
Do one of the following:
Choose New > Add Instrument Entry.
Double-click below the last instrument in the list.
Cut or copy the new entry, then paste it in the location you want in the list.
Click-hold the new entry, choose an instrument from the pop-up menu.
Click-hold the name of the instrument you want to replace in the Instrument column, then choose an instrument from the pop-up menu.
Select the instrument you want to move by clicking in the margin to the left of the instrument name.
Cut or copy the instrument.
Click in the margin to the left of the instrument list at the point where you want to add the instrument, then paste the instrument.