I have a monitor with built in speakers attached to my raspberry pie 2 running retropie 3.0. The audio is currently going to the hdmi speakers on the monitor but I want it to go to the headphone port where I have speakers attached.
I found these instructions for the raspberry pi 2 to change the audio to the audio port:
you can do this from retropie-setup under supplementary. there is also an entry on the retropie menu on ES for changing audio settings.
you can get to terminal using ssh – same as for raspbian, or by exiting emulationstation and pressing a key to drop to terminal (otherwise es restarts).