Hello. How can I send overdue invoices, from previous years that are closed, when the email on the invoice is no longer valid?

Hello, JWolf1.

Closing of books is an important feature in QuickBooks that protects against accidental changes that affect your financial reports. You'll need a pin or password to change the email on the invoice.

Just to make sure, are you login as the primary or company admin? If yes, you can re-open the closed period by clearing the closing date. You can then unlock the book by providing a new password and confirming it.

Here's how:

1. Sign in to QuickBooks Online as a primary admin or company admin. 
2. Go to Settings ⚙ and then select Accounts and Settings.
3. Select the Advanced tab.
4. Click Edit ✎ in the Accounting section.
5. Delete the date and uncheck the box. Note: To change your password, just enter a new password and confirm it.
6. Select Save and then Done.

Once done, you can open the overdue invoice and update the email address.

Please visit this link for further details about editing a closed books: Edit your closed books.

You can also review this article about recording payment for future reference: Record invoice payments in QuickBooks Online.

I'm just a post away if you need anything else. Have a great day.

It’s asking me for password to continue 

Thanks for chiming in on this thread, @Tommy31. Let me share information about unlocking your books in QuickBooks Online (QBO) so you can send overdue invoices from prior years.

Once you close your books, QBO requires the company admin of the account to create a password. It prohibits changes to entries made before a specific date and prevents messing up your data.

If you are the administrator and have forgotten the password you used to lock your books, you can replace it by following the procedures outlined above by my colleague. Otherwise, you'll need to contact the account's administrator.

Moreover, QBO includes enough tools for developing professional-looking sales forms. This way, you can adjust the layout and add special information to your invoices.

Please don't hesitate to ask for assistance whenever you have any issues handling your books. I'm always available around the clock to answer your concerns. Take care and have a good one!