There are two methods to allocate a payment to a credit note - quick pay and linking a payment from an imported statement.
Please note: Both methods do not currently support allocating a part payment to a credit note.
This method explains how to use the quick pay form on the credit note.
i. Navigate to the Sales > Credit notes menu.
ii. Click on the credit note number that you would like to apply a payment to.
iii. Fill out the details of the quick pay form to the bottom right and hit the Pay button.
The second method is to import a statement and explain a payment from the statement by linking it to the credit note.
You can also create a one-off money in/out payment on the Money > Bank accounts menu and follow steps iii - iv below.
i. Navigate to the Money > Bank accounts menu.
ii. Click on the statement that needs explaining at the bottom of the menu.
iii. Click on the appropriate payment and select the Refund tab
iv. Select the appropriate customer and hit the Add transaction button beside the credit note that you would like to apply the payment to.