When you re-book a Southwest flight at a lower cost, leaving those "funds" in your account to use on a future flight, be sure to "save" that RESERVATION NUMBER someplace, and the fact that you re-booked and now have "Saved Funds" from it. Write it on a printout of the res, or a boarding pass, something and save it. Because, when you go to use those funds for the next flight, you must enter that RESERVATION NUMBER, like XQYB7 from which the funds were earned in order for the system to retrieve and apply them toward your new reservation.
You don't have to know how many dollars are in your account since that populates automatically, once you enter that RESERVATION NUMBER (and your name) from which funds were saved. But you gotta have that reservation number!!
Hey, anything to make booking travel less stressful, right?