[Question] How do audio right?

I've been vlogging for about six months now and I think I'm not good with audio yet.

I was originally using my camera's built-in mic, but it was picking up a lot of background noise. I got an external mic, one of those rod-looking things, but it didn't seem to work well. I also had this recorder which I would use for voiceover stuff. I liked the quality of it, so I started using it for the audio for my vlogging too and syncing it to the video from my camera.

While I think it's an improvement on my camera's internal mic, I'm not sure it's perfect. I have to be careful with placement because it's stereo and if I turn it a little, it makes the audio seem like it's coming from the side.

But the hardest problem is levels. I don't even know what to aim for here. Some YouTube videos sound fine on my desktop, while others are way too loud or too quiet with headphones. My own videos seem to have the same problem. I can't find any good standard for this. My main concern is the audio levels aren't too jarring within the same video.

Anyway, I'd really appreciate some guidance on where I should go with audio here and if someone knows audio stuff, maybe you could take a look at my channel and tell me what you think specifically in regards to audio. Am I on the right track? What am I clearly doing wrong? That sort of thing. I can PM you my channel if you're interested.