“folder cannot be found”

They don’t volunteer the location of the folder. It’s pretty easy to create problems if you mess in there too much.

Click somewhere in the blank desktop.

Go (top of the desktop) > Go To Folder >
Screen Shot 2017-12-07 at 19.45.04.png
You gotta have the squiggle in there and it’s lower case “audacity.”

The mastering suite is a forum posting and a man page.

As I said, selecting the whole track for use is wrong. You can’t click above MUTE any more. The graphic got changed. You have to click lower-right in that little blank box (in zebra stripe here).
The suite of tools is intended to be stand-alone. Use all of the tools—each one depends on the others.

You are saving high-quality WAV copies of all your readings as backup, right? We can’t take effects, filters or corrections out of a performance. If you mess something up bad enough without a clean backup, you’ll have to read it again.