How can I check to make sure my HTTPS reverse proxy will use TLS 1.2?
 

When you configure the Proxy to be an HTTPS Reverse Proxy you have to add a Service called an HTTPS Reverse Proxy Service:

Configuration > Services > Proxy Services
 
On the HTTPS Reverse Proxy Service you will see that you have options where you can see the support SSL protocols for the HTTPS connection to the HTTPS Reverse Proxy:




You can select the SSL protocols that you would like to use. Please not is not advisable to use SSSLv3 or SSLv2