Turn on Track Changes
Show the changes made to a document
Select Review, and select a view option from the Display for Review list.
Simple Markup places a red line in the margin where a change has been made.
All Markup shows each person’s edits in different colors of text and with strikethrough formatting.
No Markup shows how the incorporated changes will look.
Original shows the original document.
In the Show Markup list, select the types of markups to display: Comments, Ink, Insertions and Deletions, and Formatting.
Turn off Track Changes
On the Review tab, in the Tracking group, select Track Changes.
New changes will not be marked, but changes that were already marked remain.