Komet Sales has the option to add or edit credit reasons when a user has to issue a credit to a specific customer.
Follow these steps:
Go to Setup > Settings > Order Entry, click on the Credit Reasons link.
The "Credit Reasons" window will pop-up, click on the "Add a new credit reason" link.
Enter the "Name" of the credit reason and click on Save.
If you need to edit or delete a credit reason simply, under the "Actions" column click on the "Edit" or "Delete" links.
Make Credit Reasons Mandatory
If you want that all credits created within your company to have a reason, check the option "Make credit reason mandatory when creating a credit".