All invoices that have been booked and sent from Reviso will be stored inside the platform. You will find all the invoices issued to your customers under Sales > Archive > Archive.
If you need to create a credit note based on an invoice that has already been booked you can locate the invoice in the Archive section, click on the far right icon 'Credit' this will automatically create a credit note in draft that can then be booked and emailed out to the customer or amended and then booked and emailed out.
You can also raise a credit note from scratch by selecting to create a new invoice and then prefix the net amount with a minus, this will then turn the invoice into a credit note.
You can also change the number series to a corrective number series or one you may have created for credit notes.