I agree that Google search is horrendous but Youtube is actually manageable. If you want decent recommendations you need to curate your viewing history. If you watch some random video and find a lot of annoying related videos showing up in your recommendations then go into your history and delete that one video from the history. Now Youtube will "forget" you watched that video and stop recommending things related to it.

I use Youtube in a very specific way: I subscribe to a bunch of channels that I like and only watch what those people post. My recommendations tend to be very focused around things related to my interests. Occasionally I will look up a random video for whatever reason and I'm always careful to delete it from my history unless I actually want more recommendations related to it.