To change a flight with Avianca Airlines, you have a few options. First, visit the Avianca website or app and log into your account. In the "Manage Your Booking" section, you can select the flight you want to modify. Alternatively, you can contact Avianca’s customer service for assistance with changes. Be prepared to provide your booking details and pay any applicable fare differences or change fees, which vary depending on your ticket type. If you booked a flexible fare, changes may be free or discounted. It’s best to make changes as early as possible to avoid higher fees and ensure seat availability.