If you don't want content reviewers to accidentally modify your document, you can make the document read only before sending it for review. Another method is to restrict formatting and editing.
Making your document a read-only file means that the document can be read or copied but not modified. If one of the reviewers tries to make changes to a read-only file, the changes can be saved only by giving the document a new name or saved to a new location.
Note: Making your document read only doesn't prevent someone from making a new copy of the document and saving it with a different name or in a different place.
You can restrict the editing of a document, so that the document opens in view-only mode.
You can switch from View only to other modes granted by the document owner (Editing, Reviewing).
Note: The only options that can be selected are the one(s) that the document owner has granted.
Under Editing restrictions, check Allow only this type of editing in the document, and make sure the list says No changes (Read only).
Click Yes, Start Enforcing Protection.
1. Select File > Info > Protect Document.
2. Select Always open Read-Only.
When you open a document that is shared as Read Only, you have two options.
To open the document as read only
Select Yes
To open the document in editing mode
Note: You can close and reopen the document or save a copy of the document to open in edit mode.