When logged into your account on Associates Central, you will see a Store ID at the top right for your onsite account (it may begin with “onamz“). This is your ID to track your onsite earnings (Onsite Store ID). This Onsite Store ID was created by Amazon on your behalf to ensure you are compensated when your content helps customers that encounter your content on Amazon make qualifying purchases.
Your Onsite Store ID does not affect or change your rates for traffic you send to Amazon, including your Storefront or other pages you link to on Amazon (e.g. product pages). You should continue to use the same Store ID(s) you have been using when driving traffic to Amazon.
Learn more about Earning Onsite Commissions.