1. A document reading device comprising: a document image acquisition unit that reads a document and obtains a document image; a memory that holds the document image obtained by the document image acquisition unit; a determination unit that determines whether or not a size or an orientation of the document, the image of which is obtained by the document image acquisition unit, matches a set first parameter that is related to the size of the document and a set second parameter that is related to the orientation of the document, respectively, and when the orientation of the document does not match an orientation of a medium used to output the image, front and rear end margins on the medium cannot be set; a display unit that, when it is determined that the size and orientation of the document does not match the set parameter, displays a screen to change a setting of the parameter so as to change at least one of the first parameter and the second parameter; and a change instruction unit that instructs to change at least one of the first parameter and the second parameter displayed by the display unit.