When I right-click on a feed name from the main display, a small menu pops with the option to rename the field. I then change the name of the feed.
This feed is in a folder I created. When I click on the folder to view the unread messages, the source column still shows the old name.
When I click on File->Manage Feeds, the feed name is still the same.
If this feature was intentional, I would at least add an option to apply the name change to all "name" fields.