Once teams opens up and you have signed in, go to the 3 dots in the top right-hand side of the window and on the drop-down menu select Settings
From here click on Devices in the list on the Left-hand side of the window and lets take a look at the settings
We are looking at the Microphone, Speaker, and Camera options. For the speakers as in this example above it is defaulting to something for Epson iProjector. Click on the drop-down arrow and choose the option for your preferred audio device. Typically, one of the options with Headphones or Speakers in the name. Different models of computers may have different specific wording.
You can scroll to the bottom of the window and verify the Camera is set correctly.
If you want to make 100% sure your Audio and Video are working correctly once you have made these changes and prior to an actual call or meeting, you can scroll back up and use the "Make a test call" button. Follow the prompts to record your audio and have it played back so you can hear how you sound on the other end of a call.