How to manually update apps on your iPhone, iPad, or iPod touch
  1. Open the App Store.
  2. Tap your profile icon at the top of the screen.
  3. Scroll to see pending updates and release notes. Tap Update next to an app to update only that app, or tap Update All.
How to manually update Android apps
  1. Open the Google Play Store app .
  2. Tap Menu --> My apps & games.
  3. Apps with an update available are labeled "Update." You can also search for a specific app. 
  4. Tap Update.
you can follow this link for more details:
Apple SupportApple Support
You can turn off automatic updates and update apps manually. Or you can turn on automatic updates so that you don't need to manually update each app.
support.google.comsupport.google.com
You can either update the apps downloaded and installed on your Android device individually or automatically. Updating your apps gives you access to the latest features and improves app security