To Modify a Standard Paper Size

Click Output tabPlot panelPlotter Manager. Find
In the Plotter Manager, double-click the Plotter Configuration (PC3) file you want to edit.
In the Plotter Configuration Editor, Device and Document Settings tab, double-click User-Defined Paper Sizes & Calibration to display the calibration and paper size settings.
Select Modify Standard Paper Sizes.
Under Modify Standard Paper Sizes, select the paper size you want to adjust. Click Modify.
In the Custom Paper Size wizard, adjust the printable area as necessary. Click Finish to exit the Custom Paper Size wizard.