Is there a global setting to change languages and metrics for users in different countries?
In Core, you provide the Country name at signup. This applies to your main Core company database and is set by the Owner. Based on the country you choose here, your default currency, symbols, tax codes and other settings are customized accordingly. It is set to United States by default. Check the Core Help for details.
Next, you can specify the full company address in the Company Profile screen. The country specified here determines the default currency for your Core company. You can set your default home or local currency here so that the correct amount, multiplier and symbols are used at relevant places (say, in Expense Entries). If you change the home currency here, the currency on the reports changes automatically. This selection can be overwritten at the employee level. Check the Core Help for details.
At the user level, you also get to set up your address and country in your user profile (View Profile screen). Core should adjust the number and date format (say for time entry) automatically based on these settings. This information relates to your subscription, billing and general UI. Check the Core Help for details.
At the Employees (and Vendors) screen level, you set the physical address of the employee/vendor. You can also override the default company currency here according to your location so that correct values and symbols are used everywhere. This currency setting enables your employees/vendors to log expenses in a foreign currency.
The above settings can be overwritten at the project level. In the Projects screen, you can set the address of your project as well as specify the currency to be used for it.