Movie files

I am running an experiment with 4 trials. The list of events that goes with each is a series of movies. I need for each of these 4 trials to consist of a different list of movie clips. However, as I move down the event list, the previous events in the experient reset themselves to include the movie files from the last event list created. Any advice?

Do you mean that when you press “ok next” or “ok previous” that the selected stimulus list stays the same?