My name is David.
To change the printer paper size (assuming the computer is running Windows 10), click the Start button, then Control Panel, then Devices and Printers, then click Printers or Printers and Faxes.In Devices and Printers right-click the icon for your printer and select Printing Preferences.On the Paper/Quality tab, click Advanced.In Paper Size, select the name of the paper size you wish to use.Click OK.The paper size just configured will now be used the next time you print.
Please let me know if that resolves the issue or if you need further assistance.
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Please click the Start button, then type winver in the Search or Run box and press Enter and let me know what version of Windows is displayed in the window that appears.