The primary site URL entered during signup is used as the base URL for all affiliate links. To change the URL of your website after signing up, visit Account > Profile.
Anytime you edit your website URL make sure that you have updated your JS tracking to your new website URL.
By default, affiliates are able to edit the URL to your website. This allows affiliates to have all of their quick links go directly to the URL entered. The URL is restricted to the same base URL of your website.
While we restrict affiliates to change the URL to the same domain as your website it does not prevent affiliates from entering invalid URLs.
To disable the ability for affiliates to edit the URL disable it in Website Additional Settings.
Rather than allowing affiliates to edit your site URL in their referral link consider enabling SubIds which allows the affiliate to link directly to different pages on your website.