In order to change the product quantity:
Go to the "Products".
Click on "Download" >> "Export CSV".
3. Update the product quantity in the CSV file as per your preference.
4. However, make it clear that not to change the name of any product, as this will result in a new product.
5. Once the modification is done, upload the same updated csv file.
6. Go to the "Edit" >> "Import Products". The quantity of products will be changed.
