I made a short video of my son and I sent it to two friends from my phone to their phones. One had no sound and the other did. "no sound" uses an android and the other has a phone like mine. I sent it from my phone via email (as a message is not an option) to my yahoo account...i have sound. "no sound" got a video of a friend and THAT video has sound. She is opening these on her android and using a yahoo app I belive...i sent mine to her yahoo account. The other video may have went to a different email or some other means.
Any help would do...with my settings or hers.