To change your JetBlue flight, visit jetblue.com and go to the “Manage Trips” section. Enter your last name and confirmation code to retrieve your reservation. Eligible flights can be changed online, but fare differences may apply. JetBlue has eliminated change fees for most fare types, except Blue Basic, which may incur a fee. If you booked through a third-party service, contact that provider directly. You can also use the JetBlue mobile app or call their customer service. Changes must be made prior to departure. Always confirm the new itinerary and any price differences before finalizing.
https://www.changebookings.com/change-booking/change-jetblue-flight