What is the exact meaning of "Unused Credits" in Quick Book.
Where are they comming from?

According to the following sources, "unused credits" can occur:  1)
when a customer has made payments in excess of invoiced amounts,
and/or 2) when a credit memo has been created for a customer but not
yet applied to an invoice.

"Unused Credits on customer statements" QuickBooksUsers.com (February,
2005) http://quickbooksusers.com/.forums/showthread.php3?threadid=12308

"Applying an existing credit to an invoice" QuickBooks (January 13,
2004) http://www.quickbooks.com/support/faqs/qb2004/130021.html?source=4

Sincerely,

Wonko