How do apply credit memo against closed Invoice in AR

I see that User150755 posted the following question in the Community Documents instead of the Community Discussions, so no one posted a response.
I'm copying the question here in the hopes that someone will respond
-JimD
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I am facing the issue with Credit memo.   I have created the Original Invoice, which has the Invoice and Accounting rules.    Invoice is created and closed on the same day.  So we created Standalone CM, which doesn't have any rules.  we want to apply the CM against the Original Invoice which is closed.  I have two questions. (11.5.2)

1) How to apply Credit memo against the closed Invoice?