Control notifications by app
- Open Settings > System > Notifications.
- Review the apps listed and turn off notifications you do not want.
- For apps you keep, review available banner and sound options. Leave important security, backup, and appointment alerts enabled as appropriate.
Do not disturb and Focus are related, but different
Current Windows 11 uses Do not disturb to quiet notification delivery. Focus starts a timed work session and can turn Do not disturb on as part of that session. Older guides may call related behavior Focus Assist.
Review priority notification settings if calls or reminders need to get through. Silencing a notification does not stop the app or disable the service behind it.
If alerts disappeared unexpectedly
- Check whether Do not disturb is on.
- Review automatic rules for schedules, full-screen apps, games, or presentations.
- Open the app itself to check its own notification preferences and whether the event actually arrived.
A serious warning deserves a serious check
A browser page claiming your PC is infected is not the same as a warning from Windows Security. Do not phone the number or allow remote access from that page. Close it, then open Windows Security yourself if you want to check protection.
Official instructions & further reading
Windows features and menus vary by version. These publisher resources explain the supported procedures.