sound adjustment in TRS 2019 early release

I just got 2019 installed and I have several hours of downloading from the download station. My problem is, is when downloading and installing from the download station Music plays in the background
and I have found NO way to turn it off. That means that I cannot do anything else on my computer that requires sound without this music drowning it out.

Can anybody tell me how to turn it off.

Thanks

Go to the Sound settings in the main settings menu (and not the Launcher Settings tabs).
That is - head to the Driver/Surveyor menu area after hitting Start Trainz and then look up to the Main System Menu (hamburger list) on the left-hand side right up at the top. (Looks like 3 horizontal bars).
Choose Settings...
Navigate to the Sounds Settings tab and then turn the tick off against the 'Play music in menus' label.
Et voila!