By default, Outlook clients only show basic information/details for events within your calendar, such as subject, location, start/end dates. There are times that you need to know who made the last change and when that was made. Depending on the client you are using, you may have the ability to see additional details.
At this time, Outlook on the web and Outlook for Mac clients are limited in the type of information you can view. Use these resources to access additional details:
Currently, these two clients are limited in do not provide any last modification information.
Note: This information is returned when you double-click on an event - it will be located at the bottom right of the window.
User A (owner of calendar): no modification information is presented.
User B who has read/editor permissions to User A: last modification date and user who performed the modification is returned.
User C who has full mailbox permissions to User A:
Note: if you would like to request changes to how this feature works, please use Microsoft's customer feedback site.