First go to this page under your account settings and update all relevant address fields. Then the next time you go to print a label, click on edit next to your ship from address on the right side of the page to make sure the updated address is showing before you purchase the label.
Don't forget to update the location on your listings. Go to your active listings page in seller hub, select all listings, click the edit button in the menu above your listings. From there you can use the bulk editor to change the ship from zip code on your listings to ensure accurate rates when calculated shipping is used.
