I came across this post: https://www.magix.info/us/forum/program-opens-but-only-plays-audio-through-speakers--1196262/ and followed the recommended solution there. But when I do so, I hear no sound at all. The only way I am able to hear any sound is by selecting the ASIO driver (which comes through my laptop's speakers only).
I am using MMM version 29.0.2.17 Basic (free version) on a Samsung laptop running Windows 10. My headphones work with all other programs on this laptop and on other devices.