Can't get Sound and 2 External Screens cranking all at the same time. Help please?

Hi,
I have a sound problem At first couln’t get any sound at all except when my headphones were plugged in. Accidently I tuned off one of my external screens and dada the soung on my Surface Pro 4 internal speaker started to work. When I turn the power back on, the screen works, but the sound does not. I really need the 2 big screens though so could you tell me how to get my 2 screens to both work and sound, all at the same time??
Thanks
Ed

This is Ed again
Sorry I forgot to say my hardware is the Plugable UD-3900 and the Microsoft Surface Pro 4

See above

Hi Ed,

Thank you so much for reaching out to us, I am sorry that you are experiencing issues, but I would be happy to assist!

Just to make sure I am understanding your question, you are currently having issues outputting sound to your external monitor that has speakers, but you are able your desktop and applications on this display?

If you are just experiencing issues with your sound, when you have the UD-3900 connected to the Surface Pro 4, and you right click on the speaker icon on the bottom right of your desktop, select playback devices, what item has a green check mark next to its name indicating it is the default sound device?

Thank you for your patience,
Marc
Product Owner & Technical Support
www.plugable.com/support

Hi Everyone!

We attempted to reach out to ed regarding the issues he was experiencing via email as well as this GetSatisfaction thread, but we have not received a response back.

If you are experiencing any similar issues, or have additional questions regarding your Plugable product, please don’t hesitate to reach to our support email at support@plugable.com.

Thank you for your time,
Marc
Product Owner & Technical Support
www.plugable.com/support