Playing/stoping audio from different blueprints.

I am using [this][1] awesome template (basically a slideshow)
So - working within Widget’s Blueprints - no fancy 3d space.

the question is - how to stop/fade a playing (looped) sound A and play the new sound B on action(clicking)?
The blueprints from where I activate the sound A is different from the blueprint of the sound B.

What is the simplest way to approach this? (I am bad with coding)

Thanks?! Please help.
[1]: Swipe ‘em up Template | UE4 - YouTube