iphone camera as webcam for Quicktime

I'm using Quicktime on my Mac Air to record a video using my iPhone 8 as the webcam. My problem is, rather than record just what the camera is pointed at, it also records screen on my iPhone. Quicktime records exactly what is displayed in my camera on my iPhone. EVERYTHING including the big red record button, the "switch camera" button, and the time lapse at the top of the screen is visible in the recorded video. See attached pic of my Quicktime display. How do I fix this? I don't want the big red button or the time counter. I just want to record what my iPhone is pointed at, not the screen display.