Every event in YouTrack — creating, deleting, updating a user account, project, service and so on — is logged and stored.
To review updates to your YouTrack instance, select Audit Events in the Server Settings section of the Administration menu. The target links provide access to the entities that are managed in Hub.
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Service Settings
If your YouTrack server uses a built-in Hub service, the services links provide access to internal service settings that should not be modified. For example, you can accidentally modify the Hub integration and disable user authentication.
Please, just don't.
You can also download information about any event as a JSON file for further investigation. To do so, select one or several events in the list and click the Download as .json button.