Why is the focal length of ae camera not responding?

Setting method of adjusting camera focal length in automatic exposure;

1. Right-click the newly created camera in the lower left corner of the software interface, and select OK in the pop-up dialog box.

2. Select the camera option in the properties of the timeline interface in the lower left corner of the software to find the focal length of the camera option.

3. Drag the position of the value left and right to adjust the value. The focal length attribute must be performed with the depth of field turned on.