- Tap on "Play Store" app (it looks like a shopping bag)
- Tap on the three lines in the upper left corner
- Tap on "My Apps"
- Tap on "Update All"
- You may be asked to reconfirm permissions on several apps, tap to give the permissions
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You will have to give your phone some time to download the updates. After everything is downloaded (this happens automatically), you're good to go!
You may want to make it a habit to update your phone every week or every month.