How to default the date format when supplier export the response spreadsheet (Lines Only)

Summary:

When supplier user create the response in Supplier portal for an active Negotiation, they can click "Respond by Spreadsheet", choose export - Lines only. Then the CSV file will available for supplier user after un-zip. There will be the column "Promised Delivery Date" for supplier user to input. Supplier user copied the date in the column "Requested Delivery Date" in the file. Then once the supplier user import the CSV file back to supplier portal, there is system error "The date format must be YYYY/MM/DD".

Do we have any way to default the date formate for "Promised Delivery Date" field in the response file? This will be more easy for supplier user to do the operation.