To modify a booking, find the reservation in the Upcoming tab and tap the Modify button.
Modifying reservations more than 24 hours before the start time
As long as the start time of your reservation is more than 24 hours away, you can change the date, time, or duration of your reservation.
Modifying reservations less than 24 hours from the start time
If the reservation is less than 24 hours from the time you modify, you may only extend your reservation past the end time. You cannot change the start time, nor shorten the reservation.