Try to supply full model numbers. I'll read the manual after it downloads.
The manual so far does not tell me the audio jack has volume control. For example:
"To adjust the connected audio device’s volume, you must use the
Sound Share function or connect the audio source to the TV’s HDMI (ARC) port."
Next:
"When Speaker List is set so that sound comes from external speakers only, the Volume and Mute buttons
and some Sound functions are disabled."
The manual is not clear about the Bluetooth audio but try that as it does not state but alludes it might have a volume control. No where does it show how to turn on volume control to the mini jack.

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