Cannot open "positioning" option in OSD menu

I have a problem opening the "Positioning" and "Audio" options in my OSD menu (1703FP Flat Panel). These options are marked in grey, so I can't access them. I want to change the position of screen. How can I access this option? On this webpage:  I read the following: Note: When using '2: Digital Input', the positioning adjustments are not available. How can I fix this?