Anything that you don't want affecting your recommendations should be opened in an incognito/private window. Or you can just remove it from your watch history. Anything in your feed that you don't want there hit the three dots and pick either "not interested" or "don't recommend channel". Every now and then I get some dogshit recommendations but it's mostly cool music, weird tech shit, and various outdoor activity-related things now. Another option is to only look at your subscribed feed and ditch the algorithm altogether.

Oh also install the Hbomb youtube censorship addon if you don't have it. I never see fash channels thanks to it.

2 of my relatives are pleased with the algo and here are their techniques: one literally watches the same videos over and over again for months, then switches it up, claims this primes the algo. The other uses smart tv a lot and has an almost blank account minus a few obscure music videos he uses to spawn new user accounts on Youtube and elsewhere when he gets tired of the suggestions.

The issues with youtube remind me of 2010s Pandora how you had to downvote everything and never use the like button to avoid getting it to play the same 3 songs over and over again. Its almost as if the algo is afraid of showing users novelty unless its reactionary trash or scammy weird shit.

If you use the 3 dot menu on the home screen there is a menu option called “Not Interested” or “Don’t recommend channel”. It will also give an option for “why” you don’t like that content. That has helped a lot for me.

Overall it just takes a really long time to get recommendations dialed in. I've learned to be a bit more critical of the content, especially political, that I watch.

The recency bias is a bit harder to deal with though and I'm not really sure how to overcome that. I watch some videos on insidious if I feel I'm going down a particular rabbit hole so that my feed isn't completely inundated with samey recs. Still doesn't really stop it much though.

Some general tips:

You can remove videos from your history, and they'll stop effecting your algorithm.

Blocktube is an extension that will remove specific videos and channels from view. Kinda nice if you get a chud in your feed, or if a specific video keeps coming up. I've heard youtube's built in feature doesn't always completely remove it.

On your homepage, there's a bunch of tags like "music" and "gaming". If you scroll all the way to the right, there's a "new to you" tag. I find this page has better recommendations then my homepage.

Not really an algorithm change, but if you sub to a ton of creators you like, you can just go to your sub feed. I often "re discover" channels I haven't watched in a while.

I use Freetube so I don't have to put up with Youtube's algo bullshit. You can also block channels, and I would recommend spending time blocking reactionary and clickbait bullshit. It's a vastly more pleasant experience once garbage has been purged.

I have ADHD and cycle through phases of hyper fixation pretty quickly. The algorithm you’re describing might be built for people like me (sorry!).

I find that my algorithm tends to recommend videos based almost exclusively on content from about 3 of my most recent fixations. I can usually change it up pretty quickly though. I think the trick is having a fairly robust set of playlists that I revert to whenever the algorithm fails me. This might provide some more insight to help train the algorithm, though it probably depends on a bunch of other factors.

Whenever showing me content similar to my most recent views doesn’t work, the algorithm usually just defaults to showing me cat videos. Which I’m pretty pleased with, cat videos are easily the best thing on that site.