Change in behavior is often due to illness or hormones.
Have you had your bird DNA sexed to verify that he is male?
What you are describing sounds like it could be a variety of things, including possible knemidocopatiasis (a special type of mite infestation --likely Knemidokoptes pilae or Scaly-Face Mites).
https://wagwalking.com/bird/condition/knemidokoptes-mange
http://veterinarymedicine.dvm360.com/knemidocoptiasis-birds
You should get your bird to a Certified Avian vet promptly. It may not be mites, but only a vet will be able to give you a definitive answer.
Some cere changes can be hormonal , but when estrogen-related (in females), it is my understanding that there is less of a crusty appearance and more of a flaky /brownish/tan appearance.. not white/crusty. Male birds can develop testicular tumors that can also cause cere changes (similar to those seen in females) due to production of female hormones. Hypertrophy and/or hyperkeratosis can be caused by other issues as well--- it isn't always just due to hormones (it can also be due to underlying health issues).
If it is hormonal and your bird is a female, the condition is generally harmless. You will just want to limit hormonal triggers (shadowy places, mushy foods, love interests lol, and cuddles). Also, pay attention to light-cycles (too much or too little sun can mess with hormones and consistent sleep is also important--solid 10-14 hours nightly). Even if hormonal, hypertrophy and/or hyperkeratosis can
sometimes cause the nares can become blocked and, in such cases, they will need to be unblocked.
The aforementioned suggestions for minimizing hormonal behavior apply to sexually mature birds in general (regardless of gender)--it is always best to avoid hormonal triggers (such a as shadowy places, petting down the body, too much or too little light, too much or too little sleep etc) because excessive hormonal behavior can lead to increased screaming, aggression, feather plucking and, in females, egg-laying (and potential egg-binding).
Again, I am not a vet, but if your bird has mites, your vet may treat your bird with Ivermectin (quite possibly an injection-depending on the severity). Do not try to treat mites with over-the-counter mite stuff (unless specifically told to do so by a CAV) ---these products can do more harm than good). You will want to definitely consult a vet if that is an option because treating a bird for mites when the bird doesn't actually have mites should be avoided (except when one bird in a home gets mites--then other birds are usually treated as well (even if they don't have symptoms) in order to prevent re-infection etc).
If you have any other birds, they will also need to be treated if this turns out to be mites, as they are highly contagious and can actually cause beaks to fall off etc if left untreated for too long. Again- consult with your vet, but most recommend treating all birds within the home.
Some fungal infections can also impact the cere and may look very similar to scaly-face mites in presentation.
You will need to figure out whether these cere changes are hormonal, mite-related, or something else and then proceed from there (which is why the vet is your best option at this point).