Why there was no voltage build up when the terminals are interchanged?

When the terminals of a device are interchanged, the polarity of the voltage remains the same, meaning that the potential difference does not change. In many electrical devices, especially those relying on direct current (DC), the flow of current is determined by the orientation of the circuit. If the circuit is designed to only allow current flow in one direction, interchanging terminals won’t create a voltage buildup because the conditions for current flow remain unchanged. Therefore, the system will not respond differently to the reversed connections.