Hi Denise, I’ve responded by email already but for others who seek to do the same, I’ll post the solution that worked for you here:
You can change that by setting the Transition In/Out effects to None or Fade on Settings > Media.
Also, if you choose Fade then you can set the Opening speed and Closing speed settings (in the Window section) to anything lower than the default 300 ms to make it more ‘snappy’ 🙂