Does anyone have an easy way to see who made a change to a TFS Collection's Global Settings?
You can get the information from Activity Log.
To see the Activity log, just go to http://<yourserver>/tfs/_oi
if you have admin privileges.
You can filter the activities if you know the certain identities.
You can reference below screenshot, I changed the security setting in collection level, then can find the specific activity accordingly in the log.