Can't make changes in custom settings

My Adobe was deleted in a mass change over at work. I can't figure out what is wrong. I downloaded Standard DC back onto my computer. So I go to file and click on Create-then PDF from scanner. I am in the Scan & OCR. I want to change my Custom settings. But it will not allow me too. When I just try to click on scan it tells me to put valid page dimenions .

I haven't been able to work for 2 days HELP 🙂