Foreign currency purchase on iOS issue

I have my default currency as Canadian dollars and most purchases are entered as CAD. The app works great!

But I bought some gas in US dollars and entered the amount as USD but the app converts the $33.25 US purchase into $24.71 instead of the real cost in CAD which is over $44

It looks like the exchange rate is being applied the wrong way around?

Can you explain the correct way to enter the transaction in US at the time of purchase?