Hi Donald,

i don't know how you configured the site so i'ma bit lost to tell you exactly why this happens. Normally Joomla and also JSitemap resolves dynamically the domain. Of course ensure to login also in backend using the domain with the WWW. prefix.

By the way the easiest way to ensure that a particular domain is used for the sitemap is using the parameters visible in the attached screenshot. Also clear completely the cache to ensure that the sitemap is refreshed.

Greetings,

John