bicolour LED voltage threshold switch
Here's the circuit from the other question:



The LEDs are connected together on the positive side.  To make this circuit with a bi-color LED, you will need what is called a "common anode" LED.  It will have an internal circuit like this:



That matches what your transistor circuit needs.

Many bi-color LEDs are "common cathode." Like this:



That will not work with the given circuit.

Either use a common anode bi-color LED, or two separate LEDs.

To change the voltage where it switches colors, you must change the Zener diode.

For a 5V switch-over, you'll want a 4.3V Zener diode