This sounds like the wrong way to do this.
Help me understand the situation. Am I correct:
You have made a schematic change, which resulted in a given component having a new pinout.
You updated the PCB, but cannot change the part because the pin names are wrong.
You wish to change the pin names, so the update goes through correctly?
This is wrong, because you are creating an inconsistent footprint. The schematic symbol might be inconsistent too, I have no idea. These kinds of updates are allowed, and useful from time to time, but must be done extremely carefully, to be absolutely certain that the change is correct, and will not strike someone later on (including your later self!) with a hidden surprise.
Preferably, the correct symbols are created in the libraries, placed on the schematic, updated to PCB, and there are no problems.
Sometimes you need to change a component to a different type entirely, and the pins are inconsistent and cannot be updated this way. In that case, simply delete the old PCB component, and update the PCB. The new footprint will show up.
BTW, the pictured dialog is a Pad object, not a Via.
Tim