With my BV 8000 the volume control did not work. No matter if videos from Youtube, Facebook above the browser, the volume is constantly changing. The "App Sound" app does not help. What else can I try?
First i suggest to update to the latest firmware (20171011 version at least) and then perform a factory reset. If the problem doesn't solve after this, please record a video of it so i can check properly what's going on.