I've been using MuseScore for a few years now and I just switched to a MacBook Pro. I've had this probably a few times and I can't find a way around it other than just not using headphones or earbuds. When headphones are plugged in, sound still plays through the speakers, or not at all. I tried it with earbuds yesterday and it worked fine if I rebooted the program, but now it won't work at all. At first I thought it was a hardware problem with either my headphones or headphone port, but everything else works fine with audio input, just not MuseScore.