LED Running Light MK107

I am not skilled in electronics, bought the item for my children.
my problem is the polarity of LEDs. in the manual there is the explanation cathode at the side of the labeling. on the platine the labeling is parallel to the Anode / cathode. What is the correct polarity?

thank you !
kind regards, H. Kissel[img]

If you look at the print on the board for the LED there will be a circle with a flat side.
The short leg of the LED goes in the hole closest to the flat edge.
If yo look at the LED you will also notice there is a flat edge on the LED as well this should line up with the print.

Is it possible to increase the voltage on the MK107 to 12v ? Many thanks for your help

Look in this link.
http://forum.velleman.eu/viewtopic.php?f=20&t=5134&hilit=mk107+12v