This screen is the drill down from the SAP easy access screen, accessed the following way: Tools -> Accelerated SAP -> Customizing -> Edit projects -> SAP Reference IMG (button)
From this point, perform the following drill down, as shown in the following screen (Again, in the case of this screen double clicking the paper icon or triple clicking the letters brings up a help window and the arrow to the left reveals the next level. At the final level, a run icon also appears, double click this to proceed.): Enterprise Structure -> Definition -> Logistics-General -> Define valuation level
Essentially, the next level allows no changes. The defined valuation is preset at the plant level.