How to reduce background noise while recording and how to get ride of slurs and tinny sounds.

Hello,

I am frustrated today. I have had to redo my audio. However, I have slurred and came through as loud on the audio. I've tried everything to fix it, and I end up sounding like I am talking through a tin can. How do I fix that tin can sound? I've tried every YouTube video imaginable and none of them were able to fix that.

I already know about mic positioning, and tried many ways to fix that, but I still slur no matter how far or near the mic is to me. So how do I get rid of slurring on the audio file?

Then through all the YouTube videos, I found something about Noise Gate. I've tried it, but now it sounds like I am quiet. It even messed up my computer's audio (I did get that fixed). How do I use Noise Gate while recording? I also don't see my levels when I am doing that. Also, what is the standard db on Threshold, Attach, Release and Hold on Dynamic Noise Gate?