|Announcement: Problems with Shopping Cart - read this first|
You cannot change to another currency:
Paypal cannot handle carts with items in multiple currencies. Once you started a cart you cannot add new items in another currency until you empty your cart or proceed to checkout. This don't affect your visitors, only you. Press 'View Cart" on any page, and delete all items to be able to add new item in another currency.
Another reason why all items are in USD is you are using an invalid currency mark. Always use the 3-letter currency code, like USD, EUR, GBP, AUD, CAD, SEK, etc.
You might have used an unaccepted character in either the item name or the select boxes. Please avoid quote marks, ampersand, and similar, and use their HTML counterpart: ", &, ...