Galaxy S21 Tips

One UI has an exciting privacy feature that lets you lock apps, photos, videos, and files on your Galaxy device behind Samsung's defense-grade Knox security platform. Only you can unlock it using a pattern, PIN, or passcode, or with biometrics like fingerprint and iris locks. It's like having a safe built right into your smartphone, and it couldn't be easier to set up.

When an app needs to be absolutely sure it won't be cleared from RAM by Android's memory management system, it posts a persistent, ongoing notification. Another time you'll encounter non-removable alerts is when your phone or carrier really wants you to do something, like apply an update.