I want to Change my currency to USD without change my country

Not possible. You have to use local currency for your country setting unless it is one of those special cases where items are billed in US$.

This article describes how to change your country setting and the requirements and results of doing this:

Read how to "Change your Apple ID country or region" click here --> https://support.apple.com/HT201389

Countries and regions where iCloud storage plans are billed in USD --> https://support.apple.com/HT207574