This may be an inelegant solution, but I often go to one of the documents where I want to make the changes, i.e. invoice, bill, etc. I change the name to the next name in the dropdown list and save. A message comes up and says that previous payments or credits will be unapplied. Save anyways. Then immediately change the name back to the correct name. Any payments or credits that were previously applied to that document are not any longer, and you can apply things the way you want. Works for me :)
Rochelley , Not sure if you'll get this message, but if you do, THANK YOU! Your "inelegant solution" was brilliant! For years I've been trying to figure a way around this issue.