How to edit Typing Text in timeline?

Typing text objects cannot be edited. If you are creating SWF output, you can replace the Typing Object by a Text animation, using the right-click menu. That text animation can be edited, but because it is Flash-based this is only for SWF output. You can delete that text animation, and replace it by a HTML animation, but that should be created in another application, AFAIK this is not possible from within Captivate.