Your feet are way to wide. Moving the mast back .makes sense because your back foot is too far back anyway. Your back foot should be over the foil and you should try to balance the board and foil. Pick up the board from the front foil when on land to check for front to back balance You should also have been practicing S turns while going out and back to improve your turning. Your ride also looks so pitchy it's not often leveled flight and you ride too low on the mast. Just trying to give some points to consider.
