My cockatoo was like this when she arrived and continues to misbehave occasionally, although she's *much* better than she was. I found that target training helped enormously. It gave her something else to think about besides biting and attacking (she really was dreadful, flying at people with claws outstretched to rake faces and chomp flesh!). More recently, I've added a bit of a rope playgym to our outdoor space and she spends a lot of time on that, walking up and down and swearing at the wild corellas overhead. I give her *lots* of native branches to strip (she does this for most of her day, along with shredding the cardboard boxes I put in her cage).
The thing about cockatoos is that they're probably the most intelligent birds and therefore go stir-crazy if you don't keep them gainfully employed. I'm quite sure that's how 'Setta got to such a level of aggression at her former home. So, all the time-filling solutions like training, foraging, shredding and stripping are great for birds like these. They need to have stuff to dismantle and to puzzle at.
I would recommend that you always carry a chopstick/target stick with you when handling your bird, so that you can offer it to him as an alternative bite-object or, if he does latch on, you can use it to gently disengage his beak from your flesh. Always carry treats as well, so you can reward him as soon as he shows calm normal behaviour.
Another important tool is providing lots of opportunities for flight. This uses up a lot of pent-up energy and really brings down the level of aggro you see. So, start teaching your bird to come when he's called and keep increasing the distance over which he has to fly. This has lots of benefits, from building good, strong flight muscles (helps birdie get out of a jam quickly) to building air sac capacity (vital for indoor birds) and maintaining general fitness. The best benefit, though, is knowing your bird will fly to you on command if he happens to get out!
If you persevere, your bird will respond over time and if you have the patience you can teach him a much quieter, easier way of living. It'll be great for both of you! Best of luck!