Change the language your Mac uses
Although your Mac is set to display the language of the country or region in which it was purchased, you can choose a different language to use. For example, if you bought your Mac in the United States but you work primarily in French, you can set your Mac to use French.
You can also choose different languages for individual apps. For example, if your system language is set to Simplified Chinese, but you prefer to use a certain app in English, you can do so.
Tip: If you’re using a web browser like Safari to view this page, you can read it in another language. Scroll to the bottom of the page, click the name of the country or region in the bottom-right corner, then choose a country or region in the list.
Change the system language
On your Mac, choose Apple menu
in the sidebar, then click Language & Region 
on the right. (You may need to scroll down.)Under the Preferred Languages list at the top, do any of the following:
Add a language: Click the Add button
, select a language in the list, then click Add (the button in the bottom-right corner).The list is divided by a separator line. Languages above the line are system languages that are fully supported by macOS and are shown in menus, notifications, websites and more. Languages below the line aren’t fully supported by macOS, but may be supported by apps you use, and on some websites.
If you haven’t already added an input source for typing in the language you’re adding, a list of available input sources is shown. If you don’t add an input source now, you can add it later in Keyboard settings.
Change the primary language: Drag a language to the top of the languages list.
Note: You may need to restart your Mac to see the change in all applications. Click Restart Now (the button on the right with red text) to restart your computer.
If macOS, an app or a website supports the primary language, the user interface is shown in that language. If the language isn’t supported, the next language in the list is used, and so on.
The order of the languages in the list determines how text appears when you type characters in a script that belongs to more than one language. See If non-Latin fonts don’t appear correctly.
If your Mac has multiple users and you want everyone to see the language you chose as the primary language in the login window, click the Settings pop-up menu 
, then choose Apply to Login Window. (If the Settings pop-up menu doesn’t appear, it means the login window is already set to use the primary language.)
Choose the language you use for individual apps
On your Mac, choose Apple menu
Go to Applications, then do any of the following:
Choose a language for an app: Click the Add button
, choose an app and a language from the pop-up menus, then click Add.Change the language for an app in the list: Select the app, then choose a new language from the pop-up menu.
Remove an app from the list: Select the app, then click the Remove button
. The app uses the default language again.
If the app is open, you may need to close and then reopen it to see the change.