Bluetooth Audio Drops 5-7 seconds into a video --randomly

I am using presenter hooked up to HDMI to LCD screens. For sound, we connect through Bluetooth using the ALTO Bluetooth to XLR adapter. Our church is small, and so we do not have a worship team, but we love to sing using downloaded youtube videos. We are using a Windows on a Lenovo.

The problem: Every once in a while, a song video will play about 7 seconds at regular volume, then suddenly drop to almost nothing. I've played the same video during setup and practice and it would work fine. When it happens, to get sound back, we have to switch audio to the computer speaker, then back to Bluetooth. This is the only program this has happened with. Any suggestions or theories on how to prevent it?