I think something changed in the last few days overall with YT. I have been getting recommendations for videos I watched 4 or 5 years ago and they show as unwatched.

Search on Lemmy Explorer put your search term in the box that says "Filter Communities" I only mentioned that because it's not intuitive should just say "Search" IMO

I got some good deals from the Reddit one though about 80% of the posts were trendy things that don't fit my very laid back style.

No problem glad to help a little. Keep an eye out on Lemmy Explorer you can use the filter box to search for what you need.

I used to really like running it. I had quite a lot of aggregated content on that site.

@klin On PC it's click profile then on the line that shows your username @kbin there are two very small arrows on the bottom right of the line. click the right arrow and you'll see subscriptions.