Pairing two units of the same model in stereo mode

After upgrading to most recent version of “JBL Connect” app, pairing in stereo mode is OK with media player.

But as I play songs in Youtube, it automatically switches to “party mode” (mono).

Samsung galaxy S9+.

Does anyone know how to prevent it, and keep “stereo mode” only?

By the way, I found a work-around: split screen between 2 apps, and then change focus from Youtube to “JBL Connect” in order to switch back to stereo.

Well, it works… but this is NOT a solution! :-)

JBL Connect ver. = 4.1.199

Charge-3 firmware ver = 7.3.0

Youtube ver. = 14.04.53

Thanks!