Unable to change runtime environment on server in Liferay Developer Studio

In Liferay Developer Studio, I am try to set the Runtime Environment for my local server. After selecting a runtime environment from the drop down, I then try to save the change and get the following message:

The server cannot be saved for the following reasons: [Overview] Changing runtime base directories is not supported.

Is this a change I need to do manually in a configuration file, or should I going elsewhere to change the runtime environment?

I found a way to get the existing runtime evironment changed.

I first had to go to the server properties and select "Switch Location". This moved the server properties from "[workspace metadata] to my workspace/servers/ directory.

Inside the .server file, I just had to change the runtime-id property to one of my predefined runtimes, in my case...

runtime-id="Liferay v6.2 EE (Tomcat 7)"

My Liferay server is now working as expected.