I have the same model JVC TV as well - What make & model of soundbar are you trying to connect to it and which connection cable option are you using? Is it HDMI, analog audio (3.5mm audio cable), or SPDIF (the TV only has coaxial SPDF Out and NO optical output).
I have an old Sony Blu-Ray Home Theatre System connected to the JVC TV as follows - Sony HTS - HDMI OUT to JVC - HDMI 1 INPUT.
I then went into the SONY HTS settings menu and made sure that the audio HDMI-CEC settings were set to 'Control for HDMI - ON', 'Audio Return Channel' (ARC) was set to AUTO, and the 'HDMI Audio Input Mode' was set to HDMI 1.
I then went to the JVC settings menu, selected SOUND DEVICE - and set it to ARC.
I went back to the main menu of the TV, went to SETTINGS, selected HDMI CEC and pressed the OK button to display the sub-menu, and turned ALL of the HDMI CEC options (CEC Enable, One Touch Play, Standby and Device Menu Control) to ON.
I then pressed the BACK button to go back to the JVC TV Settings menu & set the option BELOW the 'HDMI-CEC option', labelled 'HDMI Control Mode' to AUTO.
That allows the JVC TV audio to be passed through to the Sony HTS, and the volume control of the TV allows me to adjust the sound level WITHOUT having to use the Sony HTS remote - It should also deactivate the TV speakers so that the audio signal is only passed through to the connected Sony HTS (or in your case, the soundbar).
It also means that when I press the POWER button on the JVC TV remote to turn it off, it also powers off the Sony HTS - and does the reverse to turn on the TV - it also powers up the Sony HTS as well.