No Sound via HDMI
I am trying to output 7.1 surround sound out of my hdmi port, but Ubuntu doesn't give me the option to change the sound output, via the sound menu, to hdmi, only my laptop speakers. It "knows" an HDMI cable is plugged in because it changes to have multiple desktops. I have looked online for the problem, but everything was either not helpful, not for my computer specifically or too complicated. I just want a simple, step by step answer as to fix this. My laptop is a Lenovo Thinkpad Edge E520 with a core i5 and no dedicated graphics. Any help will be appreciated!