Newer style USB encoder boards have 3 pin connector for each button. Signal, LED Voltage power and ground in one cable.
Older style Control Signal and ground only. LED Voltage was delivered over separate daisy chain wire to one 5V red 2 pin connector on board.
4 Pin Buttons
The 2 pins on the rectangular platform are for control. Wire Color does not matter. Just closing a circuit. However when connecting to Encoder Board ensure both players are connected in same order. So if red button connected to port 1 (K1), do same on player 2 or else will be problems in pie.
The 2 pins close to the edge are for LED 5V. Wire color does matter (ie. Positive voltage/Negative ground)! In some cases there is a red mark on the red connector.
Rotate all Buttons so that connectors are in exact same position. This will help ensure matching correct colors for LEDS.
For me red tips are on right. So I will just connect red line to all right pins.