I'm not sure how your control panel is setup George, but you should have a speaker-looking icon in your menu bar (probably at the top of your screen). Mine looks like this:
https://www.aoaforums.com/forum/atta...0&d=1458230999
Click on that and you'll get an audio control panel that looks something like this:
https://www.aoaforums.com/forum/atta...9&d=1458230872
From there you can select your audio outputs. As you can see on mine, I've got 4 options. I suspect you are defaulted to the HDMI output, similar to what I have as first in my list. You'll notice my actual select output (hilighted) is for the Jabra Evolve 65 headset. I had to select that the first time I plugged these headphones in so that I could get audio from them.