If Joey is higher up yes he does feel more superior and will act accordingly, that is why a grey on the floor will more likely step up just about any time and a bird high up on a shoulder or higher is difficult to work with.
Also realize the honeymoon phase might be over when he was more willing to do what you wanted but now he feels more comfortable and is asserting more of his independence.
You do need to practice more patience because working with a grey will take a lot of time and progress will be made in small steps so don't rush it, take your time and things will go more smoothly.
Face it, at some point in time you will get bit, just make sure it is not your face, nose, ears or eyes that get the bite but your hand and if you see a bite is coming you can make your hand into a fist, it will be harder for Joey to get ahold of your skin.
My Josey has yet to bite me but I know the day will come she will, I will take it but I will pay attention to what led up to it and do my best to prevent any further biting.