The Konftel Cam20 has an on screen display (OSD) menu with advanced settings available.
Go to https://www.konftel.com/camera-test/ and select the camera.
You use the remote control to access this menu by pressing on the MENU button.
Now the OSD menu should appear for you.
Use the arrow keys on the remote to toggle through the menu tree and use HOME button to select and back arrow to go back.