A Company follow average stock valuation since last 5 years, now company decide to change valuation method to FIFO system, what adjustment required?

Your question is technical.

Adjustment need to be made opening balance of inventory i.e each inventory item held should be recognised at the cost. A revaluation reserve created where credit effect of any upwards revaluation recorded and devit effect of any downward revaluation recorded.A disclosure required in financial statementsIf i am wrong please correct