I don't remember exactly where, but the option is in your (web-accessible) Netflix account settings, not on your PS4 specifically. I assume it applies everywhere.
It's available in your profile if you browse to it on a computer. The apps and mobile web does not have these setting. The profile settings are global.
That's such an evil pattern to not make this accessible everywhere out at least on the app. I think I haven't logged in to the website in years.