Turn on your personal computer and launch your Internet browser.
Go to MBA.com, the official website for the GMAT.
Click "The GMAT" option and select the "Schedule a GMAT Appointment" choice.
Select the "Reschedule Your GMAT Appointment" option on the left side of the screen and then pick the "Reschedule Your Appointment" button in the middle of the screen.
Log into your GMAT account by entering your password and user name when you are prompted to do so.
Select a new date and time for your GMAT appointment. Once you pick the new time, you will need to hit the "Confirm" button before your rescheduled appointment will be finalized.