Settings>List>Ship From Address is where you enter your Ship From address, that will transfer into Seller Central when you go there to complete your shipment and purchase shipping labels.
This section is collapsable. To expand or collapse it, click the blue arrow in front of Ship From Address
You can make any of the shipping addresses Primary, which will automatically fill that address into the batch Ship From section. To change the primary shipping address, click the radio button for Make Primary next to an address
You will be asked to confirm this change. To save it, click Yes. To select a different address, click No, Go Back
To add a new Ship From address, click Add Address in the upper right corner of the Ship From Address section.
Fill out the details in the window that appears and click Save Address to save the information. You can make this address Primary as you enter it so that it shows up automatically in the ship from field on the batch creation window by default. To go back, click Cancel
If you need to delete an address, click the Trash Can icon next to it. You cannot delete the Primary address, so you would need to change that first before attempting to delete
You will be asked to confirm this change. To proceed, click Yes, Delete. To cancel, click No, Go Back
If you need to edit an address, click the Pencil icon next to it