1) If God himself never changes, the things he does, do change. In part to suit the people he addresses. To a person dying of thirst, he gives water; while a drowning man gets less water, one hopes. One day he makes a sunny day; the next, rain.

2) Cf. dispensationalism; or God giving different rules, a “new covenant,” to a different age.

3) While then too, our perception of him changes.

These things would partially account for any apparent changes in God himself.

Given these APPARENT shifts, people might be forgiven for the “error” of saying that God changes; that could be generously taken as shorthand for saying that our perception is changing. Or we are seeing an unexpected side of him.