If you're using a template that shows the name of the website in the masthead / heading of the template and you would like to change this:
If you have more than one website, this will also change the name as it appears in the dropdown list that appears in the header bar of the CMS.
If you are creating your own template, you can insert the tag [WEBSITENAME] to your template to make use of this feature. For more information on tags, visit the TAGS OVERVIEW page located in the advanced section of the Design templates area of this FAQ