The Comala Document Management app keeps a full audit trail of key events such as changes to configuration, templates and parameters.
Confluence 5.10.0 and later
Comala Document Management (formerly Comala Workflows) now uses the Confluence Audit Log.
If you were using Comala Document Management (formerly Comala Workflows) on earlier versions of Confluence and then upgraded to Confluence 5.10+, you'll see the old audit trail beneath the message about the Confluence Audit Log.
Confluence 5.9.x and earlier
The audit log is accessed in Space Tools and looks like this: