Item prices in the Store view will display in the currency set in the Currency Picker. If you want to change the currency, just click the Currency Picker and select the currency you want to use from the dropdown box. The page will refresh with your chosen currency in use.
Currency also displays on the Item Detail pages. Simply change your currency in the Currency Picker to switch to a different value.
If you attempt to change currency while items are in your shopping cart, you will receive a warning that your cart will be emptied. If you confirm the change, your cart will be emptied and your currency will change.