I can not get my audio jack to work when my monitor is connected via HDMI. I have to plug the headphones into the jack on the monitor to get sound through the headphones but I don't want it to be this way because I want to plug in a mic too. Is there a way to fix this setting or am I stuck if I decide to use HDMI?

You need to go into the sound control panel and change the default playback device to be the onboard audio, instead of the HDMI Audio device.