My Mother (non Elite) checked in yesterday for her flight. She asked me for help though as her printer was not working. I went through the process again to get the boarding passes to show up for printing. However I was not able to find the seat selector. I would have liked to move her seat to an exit row at that time.

Is the seat selector no longer available after the initial checkin? How can I change seating after the 24 hour mark online? Or is the Kiosk the only option.