Checking the sound quality mode
When you switch the sound quality mode, the indicator (blue) flashes to show the current sound quality mode. When the headset is powered on, press and hold the 
button, then press the + or - button within 2 seconds (before the power is turned off), then the indicator (blue) flashes to show the current sound quality mode.
“Priority on sound quality” mode: 3 times 
- - - -
SBC, AAC, aptX, or aptX HD is selected automatically.
“Priority on stable connection” mode: 1 time
SBC
You can switch and check the sound quality mode setting with the "Sony | Headphones Connect" app.
