To add cross references, you will need to go do the Cross References screen within Price Exports. Once cross references have been added, the export process will use your identifiers for supplier, terminal, and product.
Cross references are applied on a company-wide basis. So, if you have more than one person on your account, you may want to designate one person to manage cross references. Otherwise, please be aware that any changes made to cross references by one person on an account will be applied to all users on the account.