Michael Parker

I have just discovered your model has simultaneous audio output. Look up lg simultaneous audio output on Google and it will tell you what to do.

I do not have the same model as you but on my lg you can set it to wired headphones and internal speakers together so this might be the solution.

You will need to get LG Remote Control app for phone (free) or buy a Magic Remote. They both have the microphone button you require.

Yes Plex

Go to Settings > All settings > Connection > Device Connection Settings > Universal Control Settings