In SETTINGS › APPEARANCE, pick a language under Language. The app changes at once. Tap SAVE SETTINGS to keep it.
Steps
Tap the gear at the top right of the header. SETTINGS opens with APPEARANCE open.
Find Language.
Tap the list and pick your language. The app changes at once.
Tap SAVE SETTINGS.
The languages
English, Italiano, Español, Français, Português, Deutsch, 日本語 (Japanese), 简体中文 (Simplified Chinese), 繁體中文 (Traditional Chinese), Русский (Russian), 한국어 (Korean), ไทย (Thai) and Tiếng Việt (Vietnamese).