Hello everybody!
I've seen from the video tutorial that the IK controls for the arms can be set on World, Body or Chest, but doesn't say anything about Head. Is there any way in the rig to have the controls following the head?...
If not, can somebody give me some advice about the best and fastest way to attach the hands on the head?
Thanks a lot if anybody finds the time to answer me

It is not built in, you're correct.

You can add a new constraint to the parent of the ctlArmIk (or whatever it's called) to the head joint, or reparent one of the constraint targets to the head joint.
(you will probably have to import the reference for that to work.)

Thank you for the answer!
In the end I didnt really need to make a constraint because I managed good enough with chest-follow (he is rubbing his face).
Do you think it could be possible, to include a head-follow feature in a next version of malcolm?... I think it'll be a very nice addition, to help covering all the animation needs

Hmm, maybe so. But there will always be another constraint option we didn't cover. It's also good to learn how to customize.