Your selected country is the default regional preference for Stock Events. It helps tailor regional listings and suggestions, but it does not limit you to companies headquartered in that country.
To change it, open your Profile, select Settings, then select Country under General.
The most visible effect is in security search. Stock Events prioritizes listings relevant to your selected region, which can change which stocks, ETFs, and other securities appear and how they are ranked. This preference relates to listing markets, not only where a company is headquartered.
If you want to search another market without changing your default country, use the Exchange filter in Search.
Changing your country does not modify your existing holdings, transactions, or watchlists. It also does not change the app language or your Holdings and Dividends display currencies.
Use Language & Appearance to change the app language. Use Currencies & Holdings to change display currencies.