I am new to the iPad world, and have a question about my iPad 2. If I am listening to certain apps, such BBC World News, if I hit the big button which brings up a screen showing other apps, the BBC app remains on, at the same volume as before, even as I open other apps. Other apps, such as Al-Jazeera, cut out as soon as I hit The big button. Why the difference? Is it the app, or a setting on the app? Thanks!