The activity log is useful to pin point who brought changes to the schedule.
You will find it under the More button
Once you are in the Activity Log, you will know who changed what and when. You will be able to analyze these types of changes :
Creation of shifts
Modifications
Copies
Transfers
Publishes
Deleted shifts
It is also possible to only filter changes by Manager and/or for a specific date. See the following example :
