The location on your profile can be changed from Menu--> Settings--> Profile--> Province/Location. After that your new location will be visible on your profile but it will not automatically update the location on your listings (this needs to be done on each listing separately, if needed). However the new location will be automatically added when you make new listings.
You can change the location on a listing by clicking on the listing--> Edit item --> Additional details--> Province/Location.