I know how to activate free SSL and turn on “Always Use HTTPS”, both domain and sub-domain will be force to use SSL for all traffics.
But here’s the problem, the domain has been running for few years that many pages contain image links which is non-SSL. If “Always Use HTTPS” is turned on, some browsers (like Firefox) will block parts of the web pages (non-SSL contents) to be loaded, and this resulting the web page for not rendering/working properly (some images missing) at end-user browser.
So turning off “Always Use HTTPS” will fix the problem. but then the sub-domain will have problem. The sub-domain is programmed to redirect non-SSL to SSL by default.
CloudFlare will now redirect SSL to non-SSL.
But the sub-domain will then redirect non-SSL to SSL.
This creates an endless loop of redirection and causing the sub-domain to be inaccessible at end-user browser.
So, I propose to have a new feature that is to Activate the [Always Use HTTPS] per each domain and sub-domain: