There are 3 ways to extend the booking:
1. From Bed View - quick Extend reservation
Right-click on the selected reservation and choose the Extend reservationoption from the list. Click on the number of nights you with to add to the reservation.
2. From Bed View - Add selected nights
a) Select the nights like you do when creating a new reservation
b) Right-click on the booking to which you want to add the nights and choose Add selected nights to reservation option
> This option allows you to add nights in a different room.
3. From Reservation Form - Change reservation dates
Open the reservation window, change the check-out date and save the changes: