It's just how the symbols are paired....essentially, it's the Stock or Symbol Name. You'll notice that some do start with USD (USD/CAD, USD/CHF, etc.) and others end with USD (EUR/USD, etc.). It shows up the same way for anyone around the world...regardless of what your default currency is set to.
Just remember that buying a symbol means going long on the first currency in the name (and simultaneously going short on the second)...and on the flip-side, selling a symbol means going short on the first currency and long on the second. So if you buy EUR/USD, you're betting that the Euro will rise against the Dollar. Whereas, buying USD/CAD means you're betting that the US Dollar will rise against the Canadian Dollar.
Hypothetical example: If the US Dollar were to rise across the board, and you wanted to maximize profits, you'd Sell EUR/USD and Buy USD/CAD (and so on) to profit from both at the same time. Though I certainly wouldn't recommend holding a position in more than one currency pair at a time.
Did I confuse you yet? :P