The Immutability of God

i would love to hear a layman's explanation of the immutability of god, how god is unchanging and exactly what that means for a personal god who watches over us changeable beings. So to put it in simple layman's terms, god is side of time, and that's why he doesn't change. And thus immutable. Immutable means the same thing as unchangeable. The answer is, he's really good at multitasking, just like humans can do more than one thing at a time.