I was listening to a project on Snap with a sound file, however, I noticed that once I press the Green Flag repeatedly, the project resets, but the previous sound file overlays the new sound file that is generated by the resetted project.
In general, the Green flag doesn't stop anything running in Snap! (unlike Scratch)
If you don't want that to happen, put a [scratchblocks]stop all sounds[/scratchblocks] block there