A family of Microsoft word processing software products for creating web, email, and print documents.
There is a detailed explanation posted by Suzzanne (MVP) in a word forum on how track changes work in word 2007:-
The way tracked changes are displayed is a local setting. You can select a single color for all markup (the same for all "reviewers"), or you can select "By Author." When you choose the latter, you are giving Word carte blanche to assign colors as it sees fit. You should see each reviewer, editor, author, etc., in a different color, but there is no guarantee that the colors will be the same on your system as on someone else's, just that there will be a different color for each different "person" as defined by the UserName entered at Tools | Options | User Information.
When you send the document, the recipient will see a single color or multiple colors depending on his own local settings; there is no way you can influence this from your end EXCEPT that if you opt to "Remove personal information from file properties on save" (Tools | Options | Security), then all the markup will be in a single color, identified only as "Author."