Default Change Bluetooth profile

Hi guys,

i am new here. So i am sorry if i am asking a stupid question. I want to use my Nexus 5 in my car with the Nexus Wireless charger and of course connect it to caraudio with a bluetooth adapter.
So i bought from amazon:
HomeSpot kabelloser Bluetooth HIFI Musikadapter mit NFC

The first time i connected the device i got asked to choose the between 2 profiles. I chose "Media audio" and since then i can't change the bluetooth profile. I google it and the only advice i found was reset my phone...
I tried to clear my bluetooth cash, unpair it but nothing worked. It must be a better way than to reset my Phone to factory settings!

Thank you very much for your answers.