The account’s region is set by the region’s website in which the subscription was made. To change the country from India to Muscat/Oman, you may need to create a new account by choosing the country first: https://quickbooks.intuit.com/choose-country/.
Make sure to cancel the current account, then subscribe again with the correct country.
First, here's how to cancel:
Click the Gear icon.
Select Account and Settings.
Go to the Billing & Subscription tab.
In the QuickBooks section, click Cancel subscription.
Click Continue to cancel, then click Continue to cancel again.
Follow the online steps, then click Submit and cancel subscription.