I use several speakers throughout the house...JBL PowerUp in my living room, and a Waterproof Speaker in the bath. Forums indicate that this has been a problem for other users on the M7, and some phones as far back as the Dell Streak! Only advice I can find is re-pairing, but I've done that at Maximum volume, and the higher volume setting will not hold.
Is this a know issue? Are there any other workarounds?? Anyone else having this problem???