I wanted to major in physics when I went to college in 2013 (I’m 28 now), but had to drop out and have flushed out a lot of information. A lot of basic concepts are still there, but I’d need a lot of refreshers going back to like algebra lol. I’d love to get back in to studying in my free time, but I’ve completely forgotten how. Khan academy is great, but any other advice for reteaching and retaining would be awesome!
As you mentioned, I don’t think it gets much better than khan academy. It’s an incredible source of education and you can refresh on stuff like algebra there.
Alternatively you could watch free lectures from schools online. MIT has open lecture videos for any subject https://ocw.mit.edu/search/