I have an LG soundbar which is paired via bluetooth to my Acer laptop but also plugged in to my TV via fibre optic. Whenever the speaker function is turned off or switched to optical cable, the laptop won't play through the speaker when you go back onto BT later, even though it remains as showing "paired" in the BT admin screen. I have to delete the speaker as a recognised bluetooth device and then re- pair it to the laptop EVERY single time I want to use my laptop on it. My old computer had a bluetooth icon but it allowed me to select and deselect the speaker and other sound outputs from the bluetooth admin. Now it only gives me the option to pair of delete. Surely there has to be a fix, or is this a case of if it aint broke then let's break it by MS?

I think, you should check this with LG, Its something specific to the firmware on speakers. 

BTW, did you try any other system / OS to test the sound bar ? 

Hi,

Do you mean that no issue in your old computer, what is the system version in the old computer? Is it Windows 8.1 or previous OS? 

First, I would suggest you check the driver for the bluetooth adapter, make sure to keep installing the latest driver version.

And have you check the sound\speaker option under control panel\All Control Panel Items\Sound as the snapshot below?