How come when soft foods go stale they become crunchy, but when crunchy foods go stale they become soft?

Question

Like bread goes crunchy, and chips go chewy.

Answer 1

The water in soft foods tends to evaporate, making the remains harder. But if you start with something very dry like crunchy foods, they absorb water from the atmosphere and become chewy. Also, the gluten in goods containing wheat flour tends to change its form, with effect on texture.

Answer 2

because of moisture...dry foods attract moisture from the air and they get chewy...moist foods dry out and get crunchy