Thank you for reaching out to the QuickBooks Community, @cbloomfe-uoregon.
That's a great question. I'd be glad to provide some insights about using custom transaction numbers in QuickBooks Online.
Yes, turning on the Custom transaction numbers feature helps to change the number of previous invoices. Once done, you'll see an Invoice no. field where you can enter your numbering preferences.
On the other hand, if you get an error while the upload template requires a transaction number. You can turn off the Custom transaction numbers in your account. This way, you can import the transactions without rejecting the sales receipts numbers.
Let me show you how:
- Sign in to your account.
- Go to the Gear icon.
- Select Account and Settings or Company Settings if you're using the Accountant module.
- Choose Sales on the left panel.
- Click the edit icon for Sales form content.
- Choose the Custom transaction numbers checkbox, and then click Save.
Then, import again your sales receipts into QuickBooks. For more insights on how to manage transaction quantities in the sales receipt, please check out this article: Change the number on invoices or other transactions.
For future reference, read through this article: How to show transaction numbers on sales forms. This feature lets your customer know how many transactions they've done with you.
I'm always around here to help if you have other concerns about customizing invoice numbers. Have a great day.