"Track Changes" are turned on. In the center portion of the "File" ribbon where it shows "Tracking", simply change the top drop-down option from "Final: Show Markup" to "Final". Your changes to the document will still be recorded but, will not be shown as you type.

Here is some info on the topic that may help you: http://shaunakelly.com/word/sharing/...ngesworks.html.

Hope this helps...