Nginx & Varnish & Apache

I have CWP Pro.
I'd like to have the option to use Varnish for some of my domains/accounts.

As such I choose:
Nginx & Varnish & Apache under the Setup default Web Servers.
In the details section for this, it states:

** By default this will enable Nginx&Apache for all domains while Varnish you can enable additionally for domains you need.

However, this is not the case.
Varnish is used by default for all deployed domains and I must manually setup Nginx > Varnish > Apache > PHP-FPM on every domain I don't want to use Varnish for via the Webservers Domain Conf menu.

Any ideas why this doesn't work as expected?

Also, is there a way that clients can choose whether to use Varnish or not in the client control panel area?

Thanks,
Mark

When evaluating whether to use Varnish, I have to consider whether the added complexity layer is worth the ~20% performance gain over just Nginx -- is it worth it? Also, whether I have RAM or fast storage to burn for cache purposes. The answer to those questions is rarely yes. Only on one server for one site has it proved profitable, where the VM is a 1:1 user of the server and needs to milk all the performance it can get (high traffic, Drupal core). Generally, application-level caching and Nginx tuning have proven to be the best mix of results.