No way to edit typing I'm afraid. You might simply wish to
forego the typing and use fellow Community Expert Paul Dewhurst's
typing text animation instead. You may find it in the Captivate
Exchange. You may visit the Captivate Exchange by
clicking
here
No you cannot edit typing layer, You just can change
Background and then you must merge it into back to see typing layer
!
Typing layer even can not change in layer order ..