The document discusses modifying control properties in forms. It explains that every part of a form has properties that determine its appearance and data specifications. These properties can be modified for the entire form, sections of the form, or individual controls using the property sheet, which is a dialog box listing all available properties. The property sheet is accessed by double-clicking the relevant part of the form. Many properties can also be modified using buttons on the Form Design toolbar. Controls must be selected before modifying their properties, which is done by clicking the control so selection handles appear.