This process has gotten much easier in Clarity 2014! Now it is part of the web interface when you are logged into the Clarity Server Administrator with admin rights!
Please verify the following prior to changing the path:
The user you have configured to run the Clarity Web application has access to the configured folder.
The user that runs the task server has access to the configured folder.
Once you have verified that the above stated items are true, then simply go to Server, Settings, Backup Location and change the path in the location shown below.