If you need to change your Southwest flight, you can do so by logging into your account on the airline's website. Once you're logged in, you'll be able to view your itinerary and make any necessary changes. If you need to change your flight date or time, you'll be able to do so by selecting a new flight from the available options. If you need to cancel your flight, you can do so by clicking on the "Cancel Flight" button. You'll then be given the option to select a new flight or receive a refund for your original ticket.