To live stream using multiple cameras with OBS, follow the instructions below:

1. Set up your streaming channel if you’ve not already done so. You can find how-to instructions here if you need help or watch the video in this window.
2. To use multiple cameras, I need to create multiple scenes. The first Scene is already created when you open OBS. Now, add sources by clicking the “+” icon under “Sources” (located on the bottom/middle area of your screen) and select “Video Capture Device,” add a name if you like, click “Okay,” select your camera under the “Device” dropdown, adjust the “Preset” and click “Okay.” Adjust the size of preview to fill the entire black area of the OBS viewer.
   
3. Now that we have video, let’s also add audio. Click the “+” again under the “Sources” section and select “Audio Input Capture,” select your audio, and click “Okay.”
4. Now, let’s create the second scene. In the “Scenes” section located in the bottom-left corner of the window, click the “+” icon. You can rename the scene and click “OK.” Repeat Step 1 and add a different camera and also repeat Step 2.
5. When you’re ready to start screaming, click “Start Streaming” located under “Controls” in the bottom-right corner of the screen.
6. Move between your scenes by clicking the different scene titles. Whatever scene appears in OBS, is what will appear on my streaming channel.