Update Your Flight: After selecting "Edit," you'll be guided through the process of updating your Flight information. Follow the prompts to make the necessary changes, such as selecting a new Flight date, time, or destination. Review the changes carefully to ensure they are correct before finalizing the modification.
You can also change your Flight over the phone, but you might be charged a fee. If you’re at the airport you can use a kiosk or speak to an agent.
https://us.community.sony.com/s/question/0D5Dp00002AREoIKAX/18888291467-united-airlines-change-date-policy-step-by-step
