Re: how do i change the age of the Nokia 635?
If you are 12, then according to US COPPA laws, you would be in violation of US Federal law by lying about your age. If Microsoft finds out you lied about your age in order to use the product, they would be forced by US Federal law to disable your account, which would be rather bad, especially if you have purchased any apps that are now tied to that account.
My advice... don't do it. It just isn't worth the consequences.
It doesn't really matter if you live in another country, and you feel you shouldn't be bound to that law. Because the servers used for Cortana are based in the US, Microsoft is required to follow the law no matter where you live. Even if you could avoid prosecution due to laws in your own country, Microsoft will still shut down the account if they find out, because they will still be prosecuted for it in the US.
Just leave it alone.