TAXI.com

I recently completed a collection of instrumental tracks for film and tv and registered the copyright for the collection. In some critiques from Taxi, reviewers have mentioned the song titles aren't very compelling and after reading their comments, I totally agree. The reviewers said the song titles didn't pique their interest and would be more marketable as something else. Now I want to reconsider the song titles and title of the whole collection!

My questions:

1. What's the best way to to rename a song that is already registered with the copyright office?
2. Do I just rename it and note it in my own files, or do I need to register something with the copyright office?
3. What happens when Taxi suggests a change for a song (title, melody, etc) and you change it, does the copyright need updated?

Note: None of these songs are in the hands of a publisher or in the marketplace. I've only registered the copyright and begun submitting to Taxi.

Thank you for helping a newbie!

As a practical matter, this hardly ever comes up; when you make changes to your own work it's considered a derivative of the originally copyrighted work and is thereby covered unless you add entirely new sections (bridge, chorus, hook, what-have-you) or significantly modify the melody, in which case it may be a very good idea to re-register. Re-titling isn't much of an issue either, so long a you have a way to keep track of the original titles that your songs were copyrighted under.

Thank you for the reply, mojobone! I hoped that was the case but am still in the learning process.