Foxit PhantomPDF/Reader supports to create a PDF document directly from a paper using your scanner. PhantomPDF/Reader supports both TWAIN scanner drivers and WIA (Windows Image Acuqisition) scanner drivers.
When the "Configure scanner using scanner's interface" is graye out, please check the scanner driver type.
If it is TWAIN, you could simply uncheck this option to enable the settings for Sides, Source, Color Mode, Paper Size and Resolution.
If it is WIA, you could not uncheck this option to enable the settings because the WIA scanner driver setting could only been changed from the scanner's user interface. You need to change the settings from the scanner's user interface.