By default, Social Snowball uses your primary domain in Shopify to generate unique affiliate links. Although the root domain of affiliate links must remain identical to your Shopify primary domain, you have the ability to manually change subdomains to be anything you want.
To do this, start by heading to the Settings tab of your dashboard, and click the "Advanced" page in the top navigation.
Click the 'edit' icon, and a pop up modal will appear that lets you edit the subdomain of all affiliate links.
Important note: changing the subdomain will not only apply to new affiliate links, but will also update all existing affiliate links in your account. Your existing affiliates with links may receive an email regarding this update, depending on the status of the "Affiliate program changed" email as configured in the Creatives tab of your dashboard.