If the switch is on (default option), you can choose which announcements are sent to the bluetooth device.

if it is off, no announcement will be sent to the bluetooth device.

In any case, if the bluetooth device is not connected, all announcements will be made through the speaker of the phone.
The first choice allows you to activate or deactivate voice recognition via the bluetooth device.
If the switch is on (default option), voice recognition is done from the bluetooth device.

If the "Speed reminder" option ( settings -> Voice control ) is activated, activating the previous choice allows you to choose whether the speed is recalled by the bluetooth device or the phone.
If the second switch is on, the speed reminder is sent to the bluetooth device.
If it is off, the speed reminder is sent to the phone speaker.

In any cases, if the bluetooth device is disconnected, voice recognition is done via the phone microphone.
The first choice allows you to activate or deactivate the sending of speeds via the bluetooth device.
If the switch is on (default option), the speed announcement is made via the bluetooth device.

Activating the previous choice allows you to adjust the volume of the speed announcements or to use the sound volume of the bluetooth device.

If the second switch is on, an adjustment bar appears which allows you to adjust the bluetooth volume for the speed announcements.
If it is off (default option), the bluetooth sound volume is used for speed announcements.

If the third switch is on, an adjustment bar appears that allows you to adjust the volume of the speed announcements.
The sound level of the speed announcements is independent of the phone volume setting. For example: if the sound of the phone is muted, the speed announcements is still emitted with the desired setting. From Android 9 additional authorization is required.
If it is off (default option), the phone volume will be used for speed announcements.

In any case, if the bluetooth device is not connected, all announcements will be made via the phone speaker.
The first choice allows you to activate or deactivate the sending of audible alarms via the bluetooth device.
If the switch is on (default option), the audible alarm will sound via the bluetooth device.

Activating the previous choice allows you to adjust the volume of the sound alarms or use the sound volume of the bluetooth device.

If the second switch is on, an adjustment bar appears which allows you to adjust the bluetooth volume for the audible alarms.
If it is off (default option), the bluetooth sound volume is used for audible alarms.

If the third switch is on, an adjustment bar appears which allows you to adjust the volume of the audible alarms.
The sound level of audible alarms is independent of the phone volume setting. For example: if the sound of the phone is muted, the audible alarms are still emitted with the desired setting. From Android 9 additional authorization is required.
If it is off (default option), the phone volume will be used for audible alarms.

In any cases, if the bluetooth device is disconnected, all the alarms will be made via the phone speaker.