Physicist here. Amorphous doesn't mean it changes. Amorphous means "it has no long-range order". As opposed to crystalline solids, where this longe-range translational symmetry is present.

Glass is an amorphous solid. It's not a liquid. It has a structure somewhat similar to a liquid, but calling it "a liquid which doesn't flow" is like calling a tank "an aeroplane that doesn't fly".