backrest height:
If the backrest is low, the rider will be able to lean backward, making more room in front of their trunk.
If the backrest is high, the rider will be more upright, making less room in front of their trunk.
The back rest cane height is adjustable.
Seat depth:
Check the velcro straps behind the chair.
Are any of them made loose to make the seat deeper?
Seat height -1:
any objects under the seat?
Seat height -2:
Check the velcro straps under the seat.
Are any of them made loose to make the seat lower?