I'm a music teacher and need to be able to share the audio from one program or website through the Teams app while still being able to show myself or a different screen, in order to give instructions or explanations. I have needed this in situations like teaching guitar during the COVID-19 learning from home that we are doing in Australia at the moment. I know that Zoom has a similar function to this in the advanced options.
Thanks for your time and good luck with future updates.
MICROSOFT: Please correct my response with steps or at least MS-supported audio mixing!!!
SIMPLE ANSWER: In a meeting choose "..." > Show Device Settings. Select your desired microphone. THE GOTCHA: The fun begins (and/or my knowledge ends) when you want system audio and/or mix of both system and microphone. There are audio mixer drivers ("loopback adapter" or similar name) that you can download and install separately... but I do not consider that a usable/discoverable MS Teams feature. Worse still I don't think Microsoft offers Win10 audio mixing/loopback drivers. (I think it existed in Win7 but don't quote me.) I have this same need when taking audio notes using MS OneNote and in the past resorted to A/B loopback mixer driver (name forgotten).
As a partial hack you can share your video (which includes your microphone) but cover your camera. Net effect is your audio with video black (or yellow if you use a Sticky note).