I can't get the sound to work

I just got the 

HP ENVY Phoenix 810-160 and I can not for the life of me get the sound to work.  I am using it with a HP Envy 23 inch monitor that also has Beats audio and an HDMI cord hookup.  I have gone through all the steps on the monitor support page and the desktops support page.  Any help out there?  Thanks in advance.