There's no differences attached to currency settings, it just sounds like you've previously disabled the Common Thank You Email in the Canadian account, that's the one with the "view order" message.
You can re-enable that on the Edit Preferences screen, just make sure the Common Thank You Email box is still checked there. If you need to re-enter the message the default text is:
Subject: Your [%business_name%] purchase - Order #[%invoice%]
Thank you for your purchase. Your Invoice ID is [%invoice%].
You can view your order details at
With that in place, you can then disable the individual product emails within their own settings by unchecking the Product Thank You Email section. This will set the Canadian currency account to only send one email for each order, and the same steps will work for the US currency account as well.