Tunneling Diode Example

This example shows three figures and states that the well's energy level is quantized. By varying the source voltage, the source energy and well energy equalize thereby allowing conduction (tunneling) to occur. However, the figures seem to be incorrect in that the source energy (red line on left) seems to be at a fixed level whereas the well energy (red line on right) is changing. Am I misinterpreting these figures? (first example under "Quantum Devices" section)