How can I find out who acted on a change order and the changes they made?

Open the History tab of a change order or change request to see the sequence of actions recorded for that object. You can see who has performed each action along with the time stamp and the details about each action.

For example, you can see who approved the change order and the approval comments. You can also perform a comprehensive audit on changes by opting in for the feature Track Affected Object Redlines and Other Updates on Changes.