Once a review has been created, anyone registered in Compass can be added as either a review author (with edit access) or a reviewer (with read-only access). To change both of these designations, open the review homepage and click the Edit review button to open the form. Choosing staff members from the Author list (a) will give them edit permissions, and choosing staff members from the Reviewers list (b) allows them to see the read-only version of the review. Remember to Save when you’re finished.
Note that you can only select people who are already registered in Compass for these roles. There’s information here on how external reviewers can register themselves, after which point they’ll appear on this list for you to add.