Advice to make audio better

Rule 1 of audio restoration: You cannot improve on the original. All you can do (sometimes) is make it less worse. What that means is that you can do things like removing noise, and occasionally altering EQ to enhance or reduce a particular range, but when something is essentially missing - like it is with this recording - there's nothing useful you can do to it at all without making it noticeably worse, I'm afraid.

The fundamental problem with anything like this is that we have absolutely no idea what is missing, so there's no way it can be altered in any meaningful way at all. In this case specifically you're trying to record over a limited bandwith device which keeps shifting its quality, and the only thing that's meaningful to do is leave it exactly as it is - simply because altering it any more is only going to make it worse. It's distortion - and there is absolutely no cure for that.

You should also be very careful about what you take any notice of on YouTube about editing; as you've already noticed, a lot of people can get it wrong. Your problem is that you won't know which ones! Generally it's safer to ask specific questions here.