Rewiring jack to second number

[TP]

I have two numbers and would like to change one of my jacks to the other number. The jack is currently wired red to red, green to green, the yellow black wires are in the jack but not connected. Can I disconnect the red/green and connect the yellow/black to the corresponding yellow/black connectors, or do I need to connect yellow/ black to the red/green for the jack to be switched to the 2nd number? Also there are three wires of each color, what does this mean opposed to only two?