If you sell on Amazon.com, Amazon.ca and/or Amazon.mx, or if you have multiple Amazon accounts, you will need to configure each store separately as its own connection.
Once you've added the Amazon integration, select the relevant marketplace, and then proceed with Authorizing the connection.
The Seller ID will not change between each store connection, however, the Marketplace will.
For additional reference: Configuring Finale to push the stock levels to Amazon, eBay, WooCommerce, Shopify and other selling channels