Yeah I really don't know either... I just learned about a thing called "bluffing" that apparently sometimes happens to macaws. A period of time when they are about his age when they kind of test the boundaries and get very hormonal. Maybe that's it?? Ugh, after he got over the biting just an hour ago he was back to the sweet boy he usually is... Even letting me put him on his back and touch toes and everything.
PLEASE PLEASE PLEASE disregard that information! It is incorrect and may even lead to *WORSE* behaviors! Parrots don't "bluff". The behavior that is labeled as "bluffing" is a form of communication. You ignore it, and it could lead to actual biting. It's their way of saying "please leave me alone" or "not right now" or "I'm not comfortable with this" without actually biting. When you fail to reciprocate that very obvious communication, the bird may decide that letting you know that they aren't ready with a threat, they might decide to make the connection and bite! End result? You just taught your bird to bite!
Please read this!
Barbara's Force Free Animal Training Talk: Do Animals Bluff?
Some people might recommend clipping him, although that's illegal in birds under a year old, which your macaw falls under that category. (because you are in Sweden) He's too young to clip. Even as an adult, clipping him for training purposes would probably be against the law. (could be wrong!) I haven't seen the law, but it sounds like clipping is okay *ONLY* if you have an outside aviary for your bird, and your bird is not flight harness trained. (but you must attempt to flight harness train a bird prior to clipping them)
So you'll also need to ignore anyone who says that you need to clip him for training purposes. It is literally against the law where you live! (and we have at least one forum member who can back this information up)
My suggestion? Keep him caged - for now. You need to go back to square one and start communication through an easy to understand method. Find an object to use as a target (empty pen case, knitting needle, a chopstick, etc - doesn't matter what it is - hopefully an item he's not afraid of!), then work on target training him through the cage bars. Once you are able to get him to target anywhere within the cage, then try target training through the cage door.
If the door is cage is large enough, you can even step in and train him that way! Once he understands target training in the cage, then work on the outside of his cage. Work on the tables, the floors, the couch - anywhere he's allowed! Reward, reward, reward all desirable behavior!
Once he's target trained in the cage and various areas outside of the cage, then work on target training while on people. You *will* need the help of other people for this, but you can start with target training on you. If he's on your shoulder, teach him to walk down your arm for a reward. Reward each little step towards the end goal. Then work on that behavior with other people and getting him to walk down the arm. (it may help to hold your arm out flat or at least same level as your shoulder to make this training easier)
You can also use this target training to reinforce stepping up for a reward.
There is a lot of information in the following links (in the thread), and I recommend going through all of them and learning how to target train.
Free Training Resources | Avian Avenue Parrot Forum