Thanks for the response, @donmoss.

Yes, that does make sense. Once you followed my colleague's @IamjuViel steps, then you can open an Invoice to correct the number then hit Save. Once you've changed the Invoice Number, then it will go up from there. Here's a Community Article that explains this process more in detail with a video and steps: How to change the invoice number on sales forms.

If you need further assistance, please let me know! I'm just a Reply away.