https://www.oscommerce.com/forums/topic/514143-united-%F0%9D%94%9E%F0%9D%94%A6%F0%9D%94%AF%F0%9D%94%A9%F0%9D%94%A6%F0%9D%94%AB%F0%9D%94%A2%F0%9D%94%B0-flight-change/
After the 24-hour period,**************** Change Fees will be $200 to change the date and time of their flights. If your itinerary includes travel within the United States and Canada, there will be no United change flight fee.