Hi, Macawsarecool and new friend, welcome to the forum! You forgot to give us a very important detail and that is how long you've had him. Let me explain. Parrots are not naturally people oriented. The only reason why they learn to trust and love us is that we trick them into believing we belong to their family by stealing the babies from the parents and making them imprint to humans. And that is VERY important because a handfed bird will be able to bond deeply to a human while a parent-raised bird can become tame and learn to trust and even love a human but it will never develop the deep bond that a handfed would. But, aside from this, parrots are all one-person birds and you need to win them over. There are some birds that after lots of training and because of a sweeter natural disposition, would go to strangers but they are rare and, in all truth, I would never recommend anybody actually work in training a parrot to go to anybody (I wouldn't! too risky!). Younger birds are more tolerant, with babies usually accepting anybody's touch without biting, while older birds are much more self-assured and know their might/strength and do not suffer fools easily. So it seems to me (and I could be wrong about this because everything depends on the kind of background the bird has had) that, most likely, your bird is already an adult which would put him at older than 4.
Now, the other thing about parrots is that they observe, analyze and reach conclusions - and this is why you need to 'win' them over. Ergo, the best thing you can do with an adult rehomed bird is to leave it alone for a couple of weeks. By this I don't mean truly leaving it all alone or not allowing it come out of its cage, I mean no physical interaction, no demands, nothing that would impose upon the parrot. This is the honeymoon period and you do NOT want the bird to start resenting you and even biting you during this time because it creates a dangerous and difficult to erase precedent in your relationship. So use this time to start him on a good diet (fresh food, lots of produce, no free-feeding of protein food, etc), schedule (the light schedule should be strictly solar with full exposure to dawn and dusk), steady routine (doing every single day of the year the same exact thing at the same exact time -the time is not the clock time but the time of the day in relation to the sun, just like it would be in the wild), learn his body language (so as to avoid reaching the point where he feels he needs to lunge at you), his likes and dislikes (very useful for training and special treats) and -MOST IMPORTANTLY!- to show him that you mean him no harm, no threat in any way and no disrespect (parrots have a very well formed sense of self and what their rights are in terms of their own person/body).
So, open the blinds and uncover his cage when the first light of the morning starts at the edge of the sky (around 5:30 am this time of the year) and open the door to his cage allowing it to come out on its own (do not put your hand in there or offer a stick, let him decide). Wait about 1.5 hours and offer him his produce (with you eating it standing in front of him), wait another hour or so and offer him his gloop or whatever staple food you are planning on feeding it. If he doesn't eat it, don't worry, just leave it there. It might take a couple of days but he will eat it and he won't starve because you will feed him a good dinner of whatever protein food you are going to be using. Then spend as many hours as you can with him in the same room. Talk, whistle, sing and even dance for him but do not ask him to do anything for you, no step up, no nothing except, every now and then, offer him a treat but, if he doesn't take it from your fingers, just leave it where he can reach it and walk away (this is not a reward or even a meal when he is hungry, it's a goodie you are giving him as an offering of friendship).
After a few days of the same exact routine, he will start getting used to his new home, human, diet, etc and, in a week or two, you will start seeing a change in him. He will appear relaxed in your presence (his body will be relaxed and not tense, his feathers will not lay completely flat against his body, he will preen, eat, drink, etc without constantly looking to see that he is safe in doing this, etc) and he will start looking forward to your 'visiting' (you will see him moving closer to where you are, looking at you with expectation -for a treat
, etc). This is the time to start asking him to step up with a stick BUT do not be discouraged if he tries to bite it or moves away from it, there are birds that never learned to step up to a stick and will only do it to a hand (it can be taught though). If he is one of these birds, do offer your arm (not your hand) first (and make sure you are wearing a long sleeve something, just in case) and give the command: 'Step up!' or whatever you say (I say 'Come on'' o 'Dame la patita' to the ones that speak only Spanish). If he doesn't, repeat the command one more time but do not do it a third time, just walk away and try later. If it still doesn't work, come back and we will tell you how to teach him to do this.
Ahhh, one more thing, do not change his name. Use the same one he had from before. Parrots understand and use proper names for themselves (the ones the parents gave them in the nest or the ones we give them when babies) so changing it only confuses them and delays the transition.
Let me know if there is anything I need to clarify.