I have a notesfile on how to fix/debug things. When I started it, I would write things down after I fixed something and figured I'd need to remember it later.

Problem was, I would often forget to write things down, or naively think "that was quick to find out, don't need to write it down", which is a classic mistake of confusing post-facto mindset with pre-facto.

So now when I wonder how to do a thing, I first write down in my notesfile what my question is, so when I do resolve it I go and write down the answer to satisfy my need for closure.

this is why I have made it a point these days that when I fix an issue, I immediately go to all the forums, subreddits and stackoverflow sites where I posted the question and post the relevant solution. Its a lot of work but totally beats figuring out what you did 6 months later

That’s just karma. I have tried not to do that to myself because so many others have done it to me. Still, sometimes the answer I left is too vague to be practical.

I make a habit of turning every question I have, that I don't find an answer to in 30 min, a question AND answer on stackoverflow/stackexchange

And many times, even years later, when I google the answer, I google my name, stackoverflow, and the topic, and kapow - answer received :D