Multi-Currency
If Multi-Currency is enabled, all of the currency value fields on the ME windows will show the number of currency decimals of the Functional Currency.
If Multi-Currency is NOT enabled, the currency fields on the ME windows will show the number of currency decimals assigned to the Item Number (or Source Item).
An ME is always in the Functional Currency. Even if the ME is linked to a Sales Order in a different currency, the ME will still be in the Functional Currency.