Those kind of 'step' seats can be a problem for taller riders - unless they make the butt-stop adjustable - like the seat on the Burgman 400's.
These Asian scooters are not cut for taller American riders.....but then we buy pitifully few of their products!
A total seat rebuild would be a challenge.
I always 'sit' a scooter before buying - and even then I had to spend 3 days rebuilding my LIKE's seat. But it was flat to start with - so not so difficult.
I bought my Piaggio only after helping them unbox it so I could sit the seat - while it was still strapped to the wooden skid!
I knew I wanted it - but not without a trial sit! (6'3"+)
This was my Forza, it had the same kind of seat....but the scoot was still comfortable for me.
This owner must have had your problem with his Forza's seat...it's been modified.
Stig