Navigate to the customer's account and select the Services tab.
Find the service with the rental period you want to change and click the Rental fees icon.
In the Rental fees window, click on any date within the existing rental period.
From the pop-up menu, click Edit rental period. This will activate edit mode for the calendar.
Click on the new date on the calendar that you wish to set as the start or end of the period.
From the pop-up menu, select either Set start date or Set end date to apply the change.
Click the Save button to confirm your changes.