Select the + icon next to the Invoice Tab on the left hand side of your screen, then select "Post Credit" and follow the steps below.
Step 1 - Search for Account(s)
A new window will open where you can search the Account(s). You have the option to post a Credit for one Account or you can add another Account by selecting "Add another Account":
After adding all Accounts, click Next.
Step 2 - Post Credits
Enter the credit amounts beside each Account or select the button "$ Set all to..." to enter one amount for all Accounts listed.
Click Next to continue.
Step 3 - Setup Transaction
Enter the following information:
Classification (your company name)
Public comment (comments the customer can view)
Private comment (office-only comments)
Select the Discount/Credit Item from the list (or create a new Discount Item).
Select "post." If the post works, it will show a green checkmark.