Arduino serial informations
Once you have purchased a USB vendor ID you can edit the firmware within the Arduino installation at hardware/arduino/firmwares/atmegaxxu2/arduino-usbserial/ with your vendor ID, chosen product ID, and other USB parameters as you wish and then rebuild the firmware and upload it to the ATmega16U2 on the board via ISP.

If you do not wish to purchase a vendor ID for the time being then you can use 0x6666, the prototype vendor ID, in the meantime, but you are not allowed to make products using that vendor ID available to the public.