How to get EN to exit/close automatically when user is inactive?

[rk0101 0]

My Apple laptop's EN used to exit/close automatically whenever I close the screen or has been inactive for sometime. But as of the last couple of days, EN has stopped doing that. For privacy reasons, I want it to exit/close automatically whenever I leave my computer, and not have to manually exit it. How do I do that? I can't find it under Preferences > General