How do I change the dates into another language?

Whenever I have to pick a date on something, for example like.. April 23 2004, it always shows like this, I know it’s a Japanese calendar but I can’t seem to get rid of it, I can’t pick a year, and whenever I pick a month or day it shows comes back to whatever date it is. Every single app, I have no idea how to change it. I don’t know how to fix it.