anyone know? =/

Intervals in a chord? Carefully. You have to click on the bulb of the note, and you have to be prepared to use 'undo' in the edit tab now and again. Also, if you just want one note there, you can use the repitch tool which will set all chord notes for the written note duration to a single pitch on whatever line you clicked the mouse.

Ctrl + up / down to highlight notes within a chord

and btw wrong section

....just press the circles with the eraser..