Conservation of Charge in a circuit

In a circuit, the net charge is always preserved. This means that even if the charge moves around your circuit from one component to the other (which it does) the net charge will not change. If it does change, then it means that there is a flow of charge leaving or entering the circuit.

Let's see an example:

Graphical representation of the circuit shown as black rectangle with black circle with cross in it placed in the middle part of the upper side of the rectangle. The circle represents a light bulb and it has 12 or  5 volts. On the left side of the lower side of the rectangle the power source symbol is placed with 9 volts.

Fig. 1: Circuit with a 9 volts battery and a 12 or 5 volts light bulb.

If in a circuit a battery is generating a current of 9 volts, those will be used in the components of the circuit.

If we provide 9 volts with a battery to a component that needs 12 volts to work it won't work properly, or could not even work at all, depending on the component.

On the other hand, if the component needs 5 volts to work and we provide 9 volts, those 9 volts will be used by the component. Providing too much voltage, which can be converted into energy, to a component will cause it not to work and even break since the electrical components are not made to manage such high energy.