how to flip estimate to invoice with the upgarde - cannot locate the function to invoice

In the new QuickBooks Online (QBO) interface, you can convert the estimate into an invoice by going to All Apps > Customer Hub > Estimates. Click the drop-down button on the right side of the estimate and choose Convert to invoice.

You can also mark it as accepted to make the Convert to invoice option appear.

For other ways to convert an estimate, please see this article: Convert an estimate into an invoice.

Please let us know if you need further assistance.