Keeping a parrot on your shoulder is associated with risk, and is probably not reccommended unless you trust your parrot completely. I would suggest that you start making it clear to Mango that the shoulder is off-limits immediatly.
We made the same mistake, and let Stitch be on our shoulders in the beginning, and when he had an aggressive phase, it was a hassle. We have since stopped allowing him there, and de-training a behaviour is hard, let me tell you. He's a little cuddlebug nowadays, but he still is almost never allowed on our shoulders, the only time I allow is if he is very scared (and yes, some people will say that this is a bad idea, as when he's scared, he's more unpredictable).
Start by target training your friend, INSIDE the cage, until he's comfortable with that (I am assuming he's comfortable with taking treats from you already). DONT let him out until you got this down, as you will want a secure and non-threatening way of putting your parrot back in the cage, which isnt going to send negative signals to your new friend. This is very important.
Its easy to get carried away when you get a new parrot, but its much better that you work systematically to be sure to lay down some ground rules, and start the bonding process early on. Just letting Mango roam around the house, being the king of the hill isnt going to work long term

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Have you read the guides that people have reccommended you so far? If not they are a must read, ASAP. Michaels guides are great, easy-to-follow and have supplemental videos to help explain things (they are not as throughough as the text though so you still have to have to read the whole article!)
Here's a few links that you should read ASAP:
1)
http://trainedparrot.com/Taming/2)
http://trainedparrot.com/index.php?bid=54&article=Reasons+Why+Punishment+Should+Be+Avoided+With+Parrots3)
http://trainedparrot.com/Bad_Rewarding/There are many more, but those I consider essential for a new parrot owner, as well as this one:
DONT CLIP:
http://trainedparrot.com/Clipping/Read these, and report back on your progess and what you plan to do! We are all here to help you

!
EDIT: Updated the clipping link, it was wrong earlier.