Creating Customer account for merchant store

I have made a mobile app. I connected my app with my store. I access all data from the store using REST Admin API. First I created a development store. I tested all REST admin APIs. Perform POST requests, PUT requests, and DELETE requests. All is working well. Now I created a Merchant store. In the same way, I am accessing the data using REST admin APIs. GET requests are working well but the POST requests creating some problems. When I perform POST requests on customers’ API to create new customers. It does not give me an error but I got the wrong response. I got all the customer’s data in response. How can I create a new customer for the merchant store?

Hi - answering in this duplicate post: https://community.shopify.com/topic/2281398