Rendered title animation doesn't match play back in program

I've used the "LowerThirdSimpleBoxThin" titles preset throughout my video (which is a pain in the butt to use because the duration it's on screen is hard to change). I've lengthened the duration of the animation of the title preset by playing with the "Retime Controls" and it worked great. Or so i thought.
It's perfect when played on the edit or Deliver screens, however when the final file is rendered the title animations get all messed up and don't match the in-program play back at all. Rather than staying on screen for 2 seconds the way they do when viewing on the Deliver screen, in the final rendered file they flash on then off screen in less than a second.
I'm new to this by the way, so this could definitely be a user error.
Help anyone?
Thanks a million
Don
It's perfect when played on the edit or Deliver screens, however when the final file is rendered the title animations get all messed up and don't match the in-program play back at all. Rather than staying on screen for 2 seconds the way they do when viewing on the Deliver screen, in the final rendered file they flash on then off screen in less than a second.
I'm new to this by the way, so this could definitely be a user error.
Help anyone?
Thanks a million
Don