The first step to modifying a schematic is enter design mode. This requires that a diagram be displayed. Select Diagram / Schematic / Design mode or press F-11. The diagram will be re-displayed with a light blue grid behind it. In addition, each of the 'areas' will shown as triangles with a red hatch pattern. If you don't see the blue or red patterns, you will need to change the screen resolution to one that displays at least 256 colors. Most systems support this mode, but it must be specifically selected.
Once in design mode, the schematic may be edited. Changes are only made in memory until they are saved to disk. Once a schematic has been modified, the user will have the option of saving it as the diagram is being closed. The schematic may also be saved explicitly by selecting Diagram / Schematic / Save.