I’ve not been successful yet. I changed the tail number on the liveries aircraft CFG, as well as the one in the file for the actual aircraft. (This particular livery doesn’t have its own registration painted on)
When I look at the aircraft in the hanger, it displays the tail number I want…but when I load the aircraft in the sim, it still loads the last custom one I used. I did as instructed, hitting the clear button on the customization menu with the tail number field selected. That field is blank, so I don’t know why it’s so insistent on displaying the last one I used.