SPOTIFY ON I PHONE4 NO SOUND

Hi,Have recently moved and plugged my Simple audio listen Bluetooth speakers on and played spotify premium through speakers.....the sound has to be on max on speakers to barely hear it(before it was on 2 and really loud at previous address).When I play just on I phone4 its fine......Have tried unpugging and reloading spotify no joy!!
    I did hear someone say all apps have there own volume button but cannot fine,would appreciate if anyone has any ideas?.
Kind Regards.