If you need to change flight booking for a new date or time, it is easy and in most cases possible to do it online via airline’s website or app. Just login to your account and view your booking. Click on “Modify” or “Change” link and enter your new preferred date or time. Look for fare difference or change fee if available. In the event that you need help, you may also reach out to customer service so that they can rearrange your flight according to your new travel schedule as well.