You can make any change to your bookings before the time starts.
If a booking time has started, you will need to submit the booking with changes.
Find the booking you want to change in your Upcoming Bookings list.
Click the booking you want to change.
Then click the Change Booking button.
To change this single booking, double check 'This Booking' is highlighted, make your changes and click Next.
If you need to change all ongoing bookings, make sure to click This Booking and All Future Bookings.
Check the Summary again, and click Request Change.
The Member will be asked to accept the booking changes.
If they don't or haven't accepted the changes, the original booking is still active.
The Changed booking will show in Tasks until the Member approves the changes.