We use QB 2004. Do later versions of QB support any kind of status field where you can enter in long detailed text explaining the current status and history of specific invoices and bills? For a given invoice, you might want to document who you spoke to at the customer company and when, particularly when invoices become overdue. For Bills, you might want to enter in reminders to people like "Do not pay this invoice until they issue credit for defective part...."
The only way to do this in QB 2004 is to deface the business document, or to try to squeeze it into an extremely short memo tag that is better used to hold summary information than status.