New versions of iOS don't have the options mentioned in the second post. It seems that if iOS has some useful feature, it's guaranteed that Apple will remove it.
A few days ago I was in the middle of a phone call when the audio went dead. I thought I'd been disconnected, but then I could hear the caller talking in another room. The phone had automatically switched, mid-conversation, to a set of bluetooth speakers in the other room. So, it seems now that the only way to make sure this doesn't happen again, is to have the iPhone forget the bluetooth device whenever I'm finished using the device. What a stupid thing to have to do!
