Set AUX as Default mode in Soundtouch 20?

Hi,

 

I have successfully connected satellite box of my TV to soundtouch 20 via Y cable in AUX. Now whenever I switch on my box, speaker and TV simultaneously, soundtouch 20 switches on in Bluetooth mode by default even if the AUX is connected and actively receiving audio signal. Making it a tedious & irritating task to switch to AUX mode manually.

 

Wish to know, how to set AUX as default mode when switching on soundtouch 20 speaker and switch to Bluetooth mode manually whenever required?

 

Thanks!