Can't adjust Layout Column Width; Centered text not properly centered

I am working with a MS Word document from someone else. I opened the document in Pages which I will be using to complete the document.

I changed the Document Margins to be 1" on the left and right sides. (They were set to .375")

Under Format > Layout there is only 1 column. It says 6.15" This is wrong and I can't change it. 8.5" - 2" = 6.5". I believe that this is what is causing my centered text to not be correctly centered. It is out by about a quarter of an inch. However, the page numbers are correct.

I've checked the different formatting and I don't see anything (like a tab, etc) and the text is not indented.

Can anyone suggest why I can change the column to 6.5" or center the text properly?

Thanks