To update WhatsApp on your Android,
- Open the Playstore app.
- Go to Menu by tapping on the left hamburger icon.
- Now tap on My Apps & Games.
- It will show you the apps with the Update available.
- Scroll down and find WhatsApp from the list.
- Tap the Update button next to it.
- Wait for the update to complete.
On iPhone and Windows Phone, navigate to the appropriate app stores, find the WhatsApp application, and Update if there is any updates available.