Explanation:

- Option 1: "To change the plans" suggests altering a course of action. It doesn't relate to the meaning of the idiom "bury the hatchet."

- Option 2: "To make secret preparations to attack" implies planning a surprise assault. This is not connected to resolving conflicts or disagreements.

- Option 3: "To settle disputes" means resolving conflicts and coming to an agreement. This is the widely accepted meaning of "bury the hatchet."

- Option 4: "To hide something controversial" implies concealing a contentious issue. This again is not related to resolving conflicts.