Why Does Store Engery Not Change?

A capacitor stores energy, not charge, because the electric field created when a voltage is applied between its two plates acts as the mechanism that makes this possible.

Two conductive plates and an insulating substance called a dielectric separate the two plates of a capacitor.

Whenever charges of opposite polarity are separated, electrical energy is stored in the capacitor by the same charge present.

Therefore, a capacitor stores energy but does not charge.