To save voice messages in WhatsApp, you should first check the installed version of the app. You need at least version 2.18.10 to use the feature. Currently, even version 2.18.22 is available. (As of: 5.3.18) Your versions can be viewed in the app in the "Settings" tab under "Help". There it will be displayed immediately above. To run an update, open the App Store and tap Update All in the Updates tab. After a short time, the latest version should be installed on your iPhone.
WhatsApp: Save Voice Messages
While text messaging can easily interrupt writing, other rules apply to voice messages. So far, this was not only aborted, but completely deleted. Since version 2.18.10, however, you can leave the chat without the voice message disappearing immediately.
To use the feature, open the popular messenger and start a voice message by holding your finger on the microphone icon, if you need to cancel, then swipe up to the message to secure. If you leave the chat now and return, the voice message is still there. You can now delete, play or send it. You have the choice.