How To Default To User Country Location In Checkout?

Does anyone know how to default the checkout address fields to reflect the user location? (see image)

In the image below, the user us in Australia, the product is in Australia, I'm just wondering why everything keeps defaulting to USA?

Also, how to have currencies default to the relevant country? (USD for USA, AUD for AUS)


Settings -> Checkout

You can find default address there

For currencies please take a look at GeoIP Currencies