How to comprehend the hero,Grey Ker's ability? Whether he can multiple times change his declared action as long as he only move or attack

On the other say whether he can't change his declared action when he have moved(or used movement point) and attacked?But before that,he still can change his declared action mulitiple times?

From the FAQ

Q: How does Grey Ker's ability work? Can I declare a
Battle action to activate my Battle Cry power, and then
declare an Advance action to activate my Relentless
power?
A: Grey Ker may still only declare one action per turn.
His ability allows him to change what action he is taking
mid-turn (provided that the new action is legal), but
changing his action is not the same as declaring a new
one. For example, Grey Ker could declare a Battle action
(potentially triggering Battle Cry or a similar skill), spend
some fatigue to move, make an attack roll, and then
change to an Advance action to move his speed or to a
Ready action to place an order token.

Does that explain it?

Thanks I've learned