Hi,
Well, I don't see the problem.
You have enabled the "HikaShop currency switcher module" via the Joomla modules manager, and that module allows the customer to change his current currency.
Then, you've configured a price of 690TWD for the price of the product in that order.
And you've configured a rate of 0.032 in the USD currency.
And if you convert 690 TWD to USD with a rate of 0.032 you end up with 22.08 USD, which is exactly the amount of that order.
You say "But this order doesn't need to be switched, it's default as correct TWD". But if you have the currency switcher module activated, then the customer can change the currency himself. If you don't want customers to be able to change the currency for their purchase, then you need to deactivate that module.
You said "This time I can get the email notification. But last one no, even no in spam. It happend before too, can you fix it?". But I already told you that the problem doesn't come from us. If you have a problem to receive the email notifications from our forum, then the issue is with the provider of your email address. So you need to check with them.
You also said " And this webpage, when I click reply instead of quick reply for the attachments, all of the words I type disappear. Could you improve it?". We unfortunately cannot improve that. This forum uses the Kunena extension. So for such modifications, it would have to be done in the Kunena extension which we aren't developing.