You don't say what operating system you're on, but either way the program should be free of its Quicktime connection by this point.
If you're on Windows 10, you can try downloading and installing this old version of Quicktime. (For security reasons, you can opt out of installing the Quicktime Player itself or even change QuicktimePlayer.exe to QuicktimePlayer.old. It's really the other components you need.) See if that makes a difference.