How come Heimdall seemed to have grown dreadlocks between The Dark World and Ragnarok?

Question

In Thor: The Dark World, Heimdall looks bald, maybe because he is wearing a helmet throughout the film, but in Thor: Ragnarok he has long dreadlocks.

Where did his hair come from? Did he have hair in The Dark World?

Answer 1

He is not bald.

As guardian of the BiFrost, he appeared to keep his hair short to accommodate his helmet.

With helmet:

Without:

We can safely surmise that after he abandoned his post (because of Loki impersonating Odin) and he lived away from the city, he let his hair grow out.

Side note: In Thor's vision of Ragnarok (Age of Ultron), his hair is still short.