Sound on iPhone Safari turned on after promote pawn :)

Hello.
Playing Puzzle Storm on iPhone, Safari there usually no sound on moves, but sound turned ON after make a pawn promote. See red dynamic sign in first pic, and it disappear on the second.
ibb.co/hZRb5qz
ibb.co/D13sk1V
Do you can use this "feauture" to turn on sound before the start of solving puzzle storm? Thank you.

Hello,

To enable the sound, you need to tap on your screen (which you did for promoting), because it is considered an "active" action.
But dragging (which is I assume how you played the moves up until the promotion) on the other hand is considered as a "passive" user action, because on most website you drag to scroll down (for example when reading an article).

This will be soon included in the FAQ.