Captivate Won't Play Through Headphones

I'm using 2019 11.5.5.553. Captivate always plays audio through my computer speakers, despite having headphones connected. The headphones work correctly in all other applications, and if I publish/preview HTML in browser, the audio plays through the headphones. But playing slides in the timeline or audio from the library always plays through the computer speaker. Is there a setting that I'm missing? I see reports of this issue in other adobe softward, but not Captivate, so I figure it must be user error...?