Question about Southwest booking and changing when prices lower

I've never had any issues changing or modifying my flight online so I am kind of confused what the problem is and I apologize but I don't have any suggestions but want to follow on to see what people say.

Normally, when you access your flight info on Southwest.Com you can find your flights and select to change them. From there you chose what legs of the flight you want to change and can select another day, time or even class of ticket.

If your wifes ticket is bought under a different rapid rewards account separately you can access her flight info by having her name and confirmation number here

What may be happening is that there is only 1 seat available at the lower price, but the second seat is at the next price bucket which may wash out any savings. If the savings is enough it may be worth a call, but your original booking may have been the average of the two prices without you realizing it.