Thanks for getting in touch!
It's a great idea to change the currency of the store especially if you are planning on targeting a specific country. You should be able to make a change to the store's default currency by navigating to Settings > General, and from there you can change the currency on the store. You can see where this setting is by checking the screenshot below, taken from my test store:
If you notice that this setting is locked, we will need you to reach out to a Shopify Advisor to assist you with making the change. The best method to reach out to an Advisor is by logging into our Contact Us page. When you speak to a Support Advisor, let them know that you want to change the currency from IDR to USD. They will be able to provide you with additional support for switching your store's currency.
Let me know if you have any questions.
The reason it is locked is because if you change the store's currency, then your reports can be affected. If you have launched your store and have made sales the setting to change the default currency is locked. In order to change this, you need to contact Shopify Support.
Please let me know if you have any further questions.
I think you already placed an order. So, the setting is locked. You can't change it from your store admin.
You need to contact Shopify support to change your currency. Click the 'Shopify Support' link under the currency change dropdown.
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