FAQ: Moving an existing note
You can move one or more notes in a staff by selecting them, then using the Edit | Cut command to remove the selected notes and put them into the clipboard. You can then move the insertion point into the new location and select Edit | Paste to restore the notes in the spot.
You can also move selected notes up or down on the staff. For any selected note(s), Ctrl+Shift+(up/down arrow keys) will move the note(s) up and down on a staff.
You cannot move just one note in a chord. However, you can place your insertion point to the right of the chord member and press Ctrl+Backspace to remove the chord member.