Applicable to All Tickets: This policy applies to all tickets purchased directly through United Airlines, including non-refundable fares.
Full Refund Option: If you decide to cancel instead of changing your flight, you can receive a full refund.
How to Change Your United Airlines Flight on the Same Day of Booking
Online: Log in to your United Airlines account, go to \”My Trips,\” select the flight, and follow the instructions to make changes.
Phone: Call United Airlines\’s customer service for assistance with the change.
Airport: Visit a United Airlines counter or kiosk at the airport if you need in-person assistance.
Source: https://experience.dynamics.com/ideas/idea/?ideaid=a8fb67a1-db42-ef11-b4ac-002248500255