Apps installed from the Play Store receive official updates automatically. If you install via APK from the WhatsApp website, you'll need to keep checking back for updated versions manually.
Navigate to the official WhatsApp download page: ://whatsapp.com . download whatsapp for android 6.0.1
After manual installation, disable "Auto-update" in Play Store settings for WhatsApp, or else it may try to install an incompatible newer version later. Apps installed from the Play Store receive official