When you change those values, you change audio streams which program is using.
Then, on Android (phone, tablet, ...) you can regulate loudness of some different streams separately (music, alarm, notification).
Try to do it with your HU.

If HU does not have specific mixer for regulation, that it is only way to regulate loudness level between them, or there is no way to do this.

All NextGen are supporting TTS and all resolutions.