Controlling multiple instances of mc

I’m drawing a blank on this one and can’t think of any keywords for a search. I have multiple instances of a movie clip on the main timeline along with a button. When I click on the button I want to go to frame 1 of the _mc. Kind of a “reset”. I’ve tried -

on(release){
_root.box.gotoAndStop(1);
}

but this only “resets” one of the instances.

Help.