Posting the cost in an old date

Dear All,

I am facing this problem with my client, the System is posting cost on an old entries in a period that is closed and the audit report is extracted, so this is making a problem because it is always changing the COGS account in an old period, is there a solution for that I can stop this and make it post in a new date for COGS or there is a work around that might work in this case?

Best
HAYAN