Inquiry Regarding Changing Cost Method from Average to Actual

I am seeking guidance on the possibility of changing the cost method from average to actual for organizations that already have transactions recorded in Oracle. I came across a document that seems relevant to my query [Please refer below], but I encountered difficulties in connecting organizations with existing transactions to the new cost organization.

Could someone please provide insights or advice on how to proceed with this matter? Any guidance, tips, or relevant resources would be greatly appreciated.