Hello again, Alan!
Welcome back to planDisney! Thank you so much for submitting another question for us to answer! I would be happy to provide the information you are looking for.
Modifying your Theme Park Reservation is a simple process. First, log in to your Disneyland Account and select "My Disneyland" then click "Ticket and Reservation Details" and select "Cancel Reservation." Once you receive your confirmation of cancellation, you will be able to book a brand new
Theme Park Reservation for your new date. Before attempting to rebook, check the
Availability Calendar to make sure your desired starting theme park is accepting reservations for your ticket type on your arrival day.
To upgrade your theme park ticket, you will have to make this change at the Disneyland Resort Main Entrance Ticket Booth or at
Guest Relations. Please note this upgrade is subject to availability. Again, I recommend checking the
Availability Calendar to see if there is availability at your desired starting theme park on your extension date.
Lastly, when visiting the Disneyland Resort there are several locations to retrieve a giudemap. Please see
my answer to the other question you submitted for an in-depth answer to this question.
I hope this helps! If you have any additional questions, please continue to send them our way!
Tiffanie