Hello. I am working on a spreadsheet in Numbers. I have the columns in the first row labeled as categories. How do I keep the first row "constant" so that I don't have to keep scrolling back up to see what category I am in? In other words is there a way to keep the first row locked, so that as I move down the spreadsheet I don't have to keep going back up to see which column I should be inputting data in? Thank you in advance.