Sing and Play Over MP3

I have sync'ed the lyrics to the MP3, but want to change key. Should I create a Registration and transpose there, or is there a way of changing the MP3 itself.

I thought you could but don't see how to do it now.

If I want to save favorite instruments with it, I guess I would want to save in reg anyway.

Any advise would be appreciated.
Bernie

Bernie,
registration is the best solution to save your Mp3 with transpose.Of course you can play and sing your file on the flije,but registration is much easier way.

Thank you Dusan
Bernie