Service Config Version history is available from Ambari Web in two places: On the Dashboard page under the Config History tab; and on each Service page under the Configs tab.

The Dashboard > Config History tab shows a list of all versions across services with each version number and the date and time the version was created. You can also see which user authored the change with the notes entered during save. Using this table, you can filter, sort and search across versions.

The most recent configuration changes are shown on the Service > Configs tab. Users can navigate the version scrollbar left-right to see earlier versions. This provides a quick way to access the most recent changes to a service configuration.

Click on any version in the scrollbar to view, and hover to display an option menu which allows you compare versions and perform a revert. Performing a revert makes any config version that you select the current version.