UBB.threads PHP Forum Software Community Forums Resources and Customizing How Do I? How to change email subject line?

I want to change the email subject line for Watched Forums. I only want the email subject line to display the subject line that the user entered for the topic. So remove the words "Watched Forum:" and forum title. This would be changed for both new posts and replies.

What file(s) and line(s) do I change to do this?

I am using UBB.threads™ 7.5.4.2 on Linux.

Thanks,
Mike