Humminbird international models

Hi,

Unfortunately I have purchased a Humminbird fishfinder in the US without
knowing that on the US models the units were not configureable (I want
meters instead of feet, Celcius instead of Fahrenheit etc).

However all humminbird models also exists in international versions as well
(which are fully configureable). Does anybody here know what is the
difference? Firmware, or simply a jumper inside...?

Thanks for any tip on this issue

regards

Tor