my in car Bluetooth won't automatically connect

[AC Question]

I've recently had a Bluetooth enabled head unit installed in my car (its a pioneer branded one)
Its really annoying me that my phone (Samsung s7) doesn't automatically connect when I get back into the car. I have to either turn Bluetooth off on my phone or go in Bluetooth settings, and in the individual settings for the car Bluetooth tick "use for phone audio" and "use for media audio"
how can i make it remember these settings and just automatically connect when I get back into the car or turn the engine back on?

 

[B. Diddy]

Welcome to Android Central! Do you have any other devices that might be competing for a Bluetooth connection, like a headset or smartwatch?