Thank you for posting here in the Community. I can provide some clarification about the invoices in QuickBooks Online.
The changes to the customer information will start to reflect when you create new sales transactions. For the existing invoices, you may need to manually update them one by one.
Here's how:
On the left panel, hover your cursor to Sales.
Select Invoices.
Search for the invoice.
Click the drop-down arrow below the Actions column.
Choose View/Edit.
Additionally, I recommend visiting the following article to learn more about how to handle customers in QuickBooks: Manage your customer list.
Drop me a comment below if you have any other questions. I'll be happy to help you some more.
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