The list of 7 themes you are seeing are for WHM, rather than Cpanel.
WebHostManager is a tool for resellers to use to create/modify domain accounts
Cpanel is a tool for end users to modify/control/manage domain accounts
Any site can be viewed prior to propagation via the following url:
http://yourIP/~username/
If you need the theme changed on an account, you will need to terminate the account and recreate.....this is a really big hassle, so just contact us and we will fix it for you.