Android
Releases are done in stages, and it may take time for a new version to be available on Google Play in all countries.
Follow the link.
Tap on the Update button.
You can also turn on automatic updates. To do this:
Open Google Play.
Go to the Menu by tapping on the avatar in the top right-hand corner.
Choose Settings.
Go to the Network Preferences section.
Tap on "Auto-update apps" and choose the right option.
iOS
Follow the link.
Tap on the Update button.
You can also turn on automatic updates. To do this:
Open your device Settings.
Tap on App Store.
Turn on App Updates.