I just created a new customer and a new order/invoice for that customer. When viewing the customer record I see the correct balance on that record (850.00 Invoiced) in the buttons on the right of the customer record.
Clicking on 850.00 Invoiced I see the invoices for the customer as expected.
Next, I create a credit memo for $75 of the original invoice. It appears to be correct and when I view the customer record I now see (750.00 Invoiced), but when I click on that button to take me to the invoices for the customer I see that the new total is $900 where I would have expected it to be $750.00
Is this a bug or am I not posting a credit the correct way?
Did you create the credit memo via the Customer Refunds menu? With a positive amount?