1. View your product catalogue.
  2. Click on (P) Export to CSV button to export the entire Product Catalogue into a CSV file.
  3. Once you open the file in Excel, you may notice that the GTIN and GLN fields don't look correct e.g.  
  4. Highlight each column, and right click with your mouse. Choose Format Cells.
  5. Cick on Number and change the number of decimal places to 0.
  6. Click OK.