Generally our Dynamics GP clients who use the standard cost method to value inventory, use the Manufacturing module; and standard costs are easily managed in that module.
However the Inventory Control module can be used to accurately maintain and track standard cost items using the FIFO Periodic and LIFO Periodic Inventory Valuation Methods. Unfortunately the steps to adjust standard costs is a bit quirky. There is not a dedicated function in GP that allows you to specifically identify the standard cost items that you want to adjust.
There is a function in the year-end close routine for Inventory Control (Tools >> Routines >> Inventory >> Year-End Close) that allows you to automatically adjust standard cost to the current cost for all FIFO Periodic and LIFO Periodic items. This however does not allow you to select which items to update, what the new standard costs will be, and does not create a journal entry to revalue existing inventory in the GL; so really it’s useless.
The following is my preferred process:
1) Run a Stock Status report before any changes are made to show the inventory values with existing standard costs.
2) Change the standard cost for every item you want to change.
3) Run a Stock Status report after all the changes are made to show the inventory values with the new standard costs.
4) At this point you could enter a journal entry for the difference in inventory value as reported on the Stock Status reports, and you would be done.
But what I would do, is take the alternative step of adjusting the costs by using the Inventory Adjust Costs screen. Navigate to this screen: Tools >> Utilities >> Inventory >> Adjust Costs
Select the items and enter the new standard costs for all receipts, and Process:
This will update the receipt records and print the information you need to create adjusting GL entries.