A family of Microsoft word processing software products for creating web, email, and print documents.
Unfortunately, Word doesn't give you any control over the specific colors selected when the "By author" option has been selected for color.
What you can do is choose a specific color (for insertions, deletions, etc.) which will then apply to all reviewers. To see who has created a particular tracked change, you will then have to rest mouse pointer on the change and pay attention to the initials and user name.