On an iOS device (iPhone or iPad), you can change the language by following these steps:

1. Go to the “Settings” app.
2. Tap on “General”.
3. Tap on “Language & Region”.
4. Tap on “iPhone Language” or “iPad Language”.
5. Select the language you want to use from the list of available languages.
6. A confirmation dialog will appear asking if you want to change the language. Tap “Change to [Language]” to confirm.

Note that changing the language will also change the keyboard layout and system-wide text to the new language.

On an Android device, the process is similar but may vary depending on the device and version of Android.

1. Go to the “Settings” app.
2. Scroll down and tap on “System” or “General Management”
3. Tap on “Languages & input” or “Languages & keyboard”
4. Tap on “Languages” or “Select language”
5. Select the language you want to use from the list of available languages. Some devices will require you to tap on the “Add a language” button to see a list of all languages.
6. Confirm the change in settings by clicking on ok or save.

Again, changing the language will also change the keyboard layout and system-wide text to the new language.

Please keep in mind that depending on the phone and operating system versions, the settings location might be slightly different but the general steps will be similar.