Hello,
Changing the Automatic Cost Adjustment will not alter what is occurring. Based on what you wrote let me use this example, note I am assuming you are Standard Cost and using the Standard Cost Worksheet to roll-up cost:
January Sale:
Item X - Cost 10.00
Sold - Credit Inventory 10.00 / Debit COGS - 10.00
February 1 - Cost Roll-up for Item X, to reflect 10.10 Cost. You run the Standard Cost Roll-ups and implement. This will look at on-hand quantity and book an incremental entry for the .10 cents. So if I had 10 on-hand, I would get an entry for 1.00 debit Inventory Credit Inventory Adjustment.
Is this what you are seeing?
Hope this helps.
Thanks,
Steve