If you have raised a Credit Note against a Customer that has returned part of their Order, and they wish to use the Credit Note on a new Sales Order, you can follow the steps below:
1. Ensure you have a Credit Note created from the relevant Invoice.
These are created from a Return Authorisation.
2. Open your new Invoice you wish to assign the Credit Note to.
You will need to apply the Total Value of the Credit Note created previously as a Discount within the new Invoice. This can be done in the 'Totals' tab. You will need to change the Discount Method type to 'Value'.
3. Mark as Applied within Credit Note
Go back into your Credit Note, mark as Applied. This will prevent you from applying it to any future Invoices.