Your seating position is always assigned randomly, relative to the button in seat 1, at the start of each tournament that you play.
To find and adjust your preferred seating options on the desktop software, select:
Settings → Table Appearance → Preferred Seat
You can then customize your seating preferences according to each table size.
On a mobile device, there is no preferred seat feature. At this point, you can't change the perspective or move from your allocated seat.