To change a barcode after a stock item has been added, double click on it to open it.

As shown in the image above, right-click and choose Change Barcode. The window below will appear:

Enter the New Barcode that you wish to use and press Check.

If the barcode is available, the text shown above will appear. You can then press Save and your stock item will be updated.

If the barcode is NOT available, "Barcode In Use" will appear and you will need to choose a fresh code.