You must have more than one registered domain name in order to change the one you're currently using. Your active domain name is shown in the address bar at the top of the browser when visitors access your website. All other domain names registered with your plan will redirect to your active domain.
If you have multiple domain names for a website, you can set which domain is the active one.
Click on the Webador logo in the top left corner of the Editor.
On the My sites page, click on My subscription.
Select the domain name you want to activate and click on the Use as primary domain name (home icon) button.