[Zubersoft]

You need to press down to place the start of the staff (and pause for a second to switch from placement to sizing), then with your finger still down, drag to the right to extend the staff. If you pause with your finger still held down, it will place a single line end. If you continue holding, it will then switch to a double line end. You can check the manual for details on this along with pictures showing each phase. You can also change the size of the staff by dragging up or down after the initial placement. 

Mike