I want to zoom the camera to look the picture . How to change the default zoom to focus on one area?

Unfortunately, CAM313 doesn't support autofocus/manual focus features. That said, you can only control the focal point under our recommended working distance: 40 cm - 100 cm (1.31 feet - 3.28 feet).
 
https://www.avermedia.com/us/product-detail/PW313
 
 
We understand that this may not have been what you wished to hear. If you have any other questions, please feel free to contact us.