Android

1. Open the Settings app, and navigate to the System tab. If currently in a language other than English, look for the gear icon.
2. Select Language and Input. If currently in another language, look for the icon with an 'A' in a box.
3. Select the Language option. This will always be the first option.
4. Select the language you wish to change to.

iOS

1. Open the Settings app. It is the gear icon.
2. Tap General. It has a similar gear icon.
3. Scroll to the end of the list and tap Language and Region. It is right above the option that begins with iTunes.
4. Tap (Device) Language. It's the first option.
5. Select whichever language you prefer then tap Done at the top corner and confirm.