Who was responsible for the shipTitanic's collision with ice bergs

The Titanic accident was a real event that the ship collided with ice bergs and was sunk. The same was written as a story and released as the film "Titanic'.

After watching the film, can you tell me what was the reason for the collision, and who was responsible for the collision at sea? Is it the Captain of the ship or the Navigating officer of the ship or the Duty officer on watch or the men who were on the wheels?