Hi,
Your question is confusing.
The Sale Price is different than the Material Cost Price. It is the Material Cost Price which can be Standard or Moving Average.
The Customer is not refunded the Cost Price but the Net Selling Price. The Cost Price is only for statistical purpose in the Order.
Could you clarify what you are alluding to when you say customer is paid " Moving average price was reduced the total credit to customer was $76.?"
Are you meaning Selling Price instead of Cost ? If it is selling price you should try the ideas proposed by others of changing the Pricing Date for the Return to the Original Sales Order date first and check.
If not, then check the Item Level Copy Controls from the Original Sales Order / Billing to Return Sales Order and make sure that the Pricing Type indicates Copying all Pricing Elements Unchanged like in C, D, G, Etc.
Tell me if you need more inputs.
Thanks.