GSC has a setting to choose preferred country. Go to GSC and select USA. Your site ranks where your potential audience are coming from. If your site is ranking in India, then you are meeting with their search requirements. You should target keywords that the audience from USA are search for, to rank there. Moreover, site relevance is also important. If your language settings and backlinks are coming from India, then Google assumes that you are catering to Indian audience. The last thing is that the same keywords might have high competition in USA and low comp in India, so you are able to rank here easily. In that case, you may lose rankings if you change the country. There are a lot of factors affecting rankings and it can't be easily explained.
