I have not used Flow Simulation.
Since you state that you are supposed to see a more button, you might be following some training manual ? You are on SW 2015 are you following an older training manual? Maybe it´s not needed anymore in SW 2015 to do the next step !
But, in general if there is a "more" button in some software it will turn itself into "less" button, I do not see that either.
Have you tried clicking the "Flow Trajectories" both in animation and in the design tree ? and maybe before you want into the animation. I would try both left and right click.
But these are only my wild guesses.
I guess you are right.
I am on SW2015 and that's the reason I can't find the "less" button.
what are you trying to do?