Is Bluetooth open to public?

[Bdaly]

Was sitting in the living room and the phantoms started to play music ( very loud) without me turning anything on and nobody else was home. I had to turn the power off to the speakers for it to stop. I live in a apartment building so I was wondering if someone access the phantoms Bluetooth or wifi? I have had the speakers for four months now and never had this problem. I have two silver phantoms and the dialog box and nothing else, tidal for music. How can I stop this from happening again? Thanks