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.
Change the system language
On your Mac, choose Apple menu
.Click General.
Do any of the following:
Add a language: Click the Add button
, select one or more languages in the list, then click Add.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, messages, websites and more. Languages below the line aren’t fully supported by macOS, but may be supported by apps that you use, and shown in their menus and messages and on some websites.
If you can’t use the input source that’s selected in the Input menu to type a selected language, a list of available sources is shown. If you don’t add an input source now, you can add it later in the Input Sources pane of Keyboard preferences.
Change the primary language: Select a different language in the languages list.
If macOS or an app supports the primary language, menus and messages are shown in that language. If it doesn’t, it uses the next unselected language in the list, and so on. The language may also be used on websites that support the language.
The order of the languages in the list determines how text displays when you type characters in a script that belongs to more than one language. See If non-Latin fonts don’t appear correctly on Mac.
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 Action pop-up menu 
, then choose Apply to Login Window.
Choose the language you use for individual apps
On your Mac, choose Apple menu
Click Apps.
Do one 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.