Using External camera and speaker by Zoom Android

HI. I'm using Zoom app with an electronic whiteboard (Android).
I'd like to use a web camera(external camera) and a speaker to the online meeting by the electronic whiteboard.
Where can I switch a web camera from a built-in camera?   
Actually, when I use Zoom for Windows, I can choose a web camera or a built-in camera. ( I can select a Speaker, too. ) But I can't find the settings menu for Zoom Android.  Could anyone help me how to switch a web camera / a speaker?