Enterprise users can set up purchasing and selling currencies in the Settings area on a per-Office basis.
To set up your purchasing currency:
Go to Settings > Offices.
Select an Office, then select 'Currencies' in the sub-menu.
In the top section you will see a list of your current purchasing currencies. Click "Edit" and select the currency (or all of the currencies) that your company uses to purchase products.
Click "Update Purchasing Currencies" and you're all set!
To set up your selling currency:
Go to Settings > Offices.
Select an Office, then select 'Currencies' in the sub-menu.
In the bottom section you will see a dropdown menu of selling currencies. Select your default selling currency from the menu.
Click "Update Selling Currency" to save your changes.
These purchasing and selling currencies are specific to each company Office, so if your company has multiple Offices, just repeat the above steps for each Office.