Both Beets and Picard are good. I used Beets a lot, but the command line interface can be annoying. I would try Picard instead if I had to do it again.
I know a few "rational" average men and women who know nothing about computers, and talk to their AI as if it was a human being. It's a very thin line between "yes I know it's a computer" and "it's a talking application which makes it almost human and let's forget about this detail." Those people are not religious or something. You could compare it with someone who shouts at his TV because his hero is about to do something stupid. They know it's fake, but deep down they react as if it was real.
France: the French revolution was poor people rioting. We are starting to accept that it was rich people killing each other to replace monarchy, and using poor people as a side-effect, kind of like... what we have right now, what a coincidence!
You already have good answers but it's worth repeating: It's a beginner issue, coding is hard, it took months for me to "click" and understand what the fuck was happening. Don't give up, you're the best!
I'm pretty sure they have nothing to hide...