Your step by step answer is under the link I sent to you in my earlier comment. Have you missed it? It does exactly what you need: keeps the automatic updates, and disables the restart.
Apart from that, you should aquire a habit when you're doing word processing work:
CTRL + S
Yeah, that's it. If you're ready with a unit, or you have to leave the computer, you just do a quick CTRL+S, and you're safe.
When I'm typing something, I don't even notice that I pressed it, I just do every so often. (I'm touch typing, btw.)