Once an invoice has been finalized and sent, it’s not possible to edit it. If you need to make changes to an invoice that you’ve already sent, you will need to cancel the original invoice (to avoid your customer paying an out-of-date invoice) and create an updated one.
To Cancel an Invoice
Navigate to the Invoicing Dashboard
Click the blue drop-down arrow on the far right of the invoice
Select ‘Cancel’ from the drop-down
To Create a New Invoice Based on the Canceled Invoice
Navigate to the Invoicing Dashboard
Change the filter Type to 'Archived'
Click the blue drop-down arrow on the far right
Select 'Duplicate' (This will duplicate the original invoice, so you can use that as a starting point to make your edits)
After making your edits to the new invoice, send the new invoice to your client
Following this process ensures that each edit has an incremented invoice number.