Choose the arrow tool in the toolbar. You can move notes within a beamed group, keeping the stems and beams intact by double clicking on a note within the beamed group and selecting Adjust Note from the Edit menu.
Now you can move a note within the beamed group with the keyboard cursor arrow keys or by holding down the left mouse button and dragging the note to a new position. You can select a new note within the beamed group by clicking on it with the left mouse button.
When you have positioned the note(s) as you want them, press ENTER or click the right mouse button to complete the operation. To cancel the operation, press ESCAPE.
Adjust notes within a beamed group