Why was my region defaulted to Japan? I'm in the US

Created a TT acct months ago and just got around to messing with it now. I go into settings and see my region is set to Japan. Huuuuh, that's weird, let me just set it to the United States cuz that's where I live. It wont let me change it!!! WHY??? Ends up giving me message below. How am I supposed to use in the United States for 60 days when I've already here lol. What's region even do? How does it being Japan affect the page?

https://preview.redd.it/q12vokce09rf1.png?width=573&format=png&auto=webp&s=77005aed8cfc4456be429ecba74f36bf7dc08627