"Daddy, that's a lot of red." My daughter said when she saw what I was doing. It turns out that I was right about proof reading a hard copy rather than a digital one, it's less efficient but the changes actually got made, and they are a higher quality.
It took about four hours to read through twenty thousand words and I'm currently about one third of the way through making those changes. Some of the editing is easy, forgetting a comma or coming up with a better analogy but some is much harder. There were sections where I couldn't scribble lists of things to add fast enough and hopefully I can remember the entire conclusion I was trying to make.