I cannot get rid of proxy from my computer

I was able to download videos using different programs on Chrome and Firefox. After I used some proxy programs on Firefox and Chrome, I can no longer download videos. I think it's a proxy problem. When I went to Chrome Inspector and checked media, the video URL address kept having "proxy[...]" in front of the actual address, so I suspect a proxy problem. I removed all the proxy programs but I think my computer is still "infected" by one or more of these proxy programs. How do I check to see whether these proxy programs are still on my computer and get rid of them. I went to Network, and chose "advanced" and "proxy" and then I unchecked all the boxes include "auto proxy discovery" and I chose "Passive FTP mode".

I restarted my computer, but when I check again, the address is still "proxy[...]" and I can't download videos off the web using the downloading programs.

So I am stuck and I don't know what to do.

What I want is to go back to what I was doing in the past, which was able to download these videos using Chrome and Firefox. I don't want to use a proxy program ever again.