It's best to make address changes on the website, not the app where fields are limited @b_d_smith . Take the pieces below that are relevant to your current seller status.
First go to Account Settings > Addresses and update all relevant address fields.
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Next, update the location on your listings. Item location on your listings is not linked to your registered ship from address and has to be updated separately.
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 Item Location zip code on your listings to ensure accurate rates when calculated shipping is used & better estimated delivery dates.
You'll also need to update any templates, and any time you 'sell similar' or 'relist' from a listing that had the old location you'll have to update the location on those, too.
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Finally, the next time you create a shipping label, click 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. Double-check even if the visible return address is correct as there is a different field for ship from.
If you don't see this option then you may be on the simplified label page. On the top right you'll see a link to switch to advanced shipping options.
