Create a Credit Note based on an Invoice
Make sure the Invoices & Payments tab is selected and select the invoice you want to base the credit note details on.
Press the dropdown arrow under the Convert button.
From the dropdown menu, choose To Credit Note.
The credit note will be created and opened in a form allowing the details to be edited. The form should look something like the following.
Edit the credit note as needed. Press the Close & Save button to save any changes you make.