How can I block people from using QuickTime ?

John,

you can block Quicktime Streaming using Application Filter. Create a new Application Filter under Objects > Policies > Application Filter. Apply the Application filter to a Policy rule Lan to Wan.

Hi John,

Please refer this link to configure Application Filter. Instead of selecting high risk applications, you can select custom application as per the requirement,

https://community.sophos.com/kb/en-US/123102

Hope that helps :)