The "preferable content" is just a joke to throw you off, I set my language to English, and English only, yet it still throws content in my face on my for you page, in a language I either can't understand or just don't like the content creators of, like hungarian. Sometimes after I press "not interested" on a video I didn't like (either the content creator or the video it self), i press restart as it is suggested in order for it to actually work, but after I do restart, nothing happens.