Having trouble stopping movie clip from looping in main timeline in HTML5 canvas

Hi, I'm very new to Adobe Animate, and I'm having some trouble stopping a movie clip from looping in the main timeline. 

The movie clip itself stops where intended when open - I just used this.stop(); at the end of the last tween, but when I return to the main timeline, it just continues, and using f9 to add this.stop(); to the layer itself doesn't seem to do much. 

Any help is very appreciated. Thank you!