To modify your ITA Airlines flight booking online, access the official website and log in to your account or call 1-818-878-8939. Locate the "Manage Booking" or "My Trips" section, choose the specific reservation you wish to change, and follow the provided instructions. Depending on the airline's policies, you may be able to adjust dates, times, or other details by calling 1-818-878-8939. Be aware of potential modification ITA Airlines change flight fees, and review the terms and conditions before finalizing any changes. Confirm the adjustments to secure your updated ITA Airlines flight reservation.