To change a Southwest flight reservation:
Go to the Southwest Airlines "Change Flight Reservation" page.
Input the confirmation number and the first and last name of the person who originally booked the flight.
Check the box next to each flight you want to change.
Input the new dates and destinations, then click “Select New Flights.”
Look at the available options and select your new flight.
Review your changes and click “Continue.”
Click “Purchase” to complete the transaction.
You will receive a confirmation email containing new flight information after completing these steps. Alternatively, you can change your flight by calling Southwest's reservation department at (800) 435-9792 no later than 10 minutes before your original departure. The representative will ask for your confirmation number, so have it ready. You must also provide the first and last name of the person who originally booked the flight.
Southwest never charges any fee to change your flight reservation. You may be asked to pay the difference in fare if the new flight you're choosing is more expensive than your original booking. But if your new flight costs less, you'll be refunded the difference.