Whenever you start using your shiny, new Z10 – you’ll probably find the option to toggle silent mode in the settings pull down on the main screen.
BUT! If you go into notifications and select a different quiet profile, your BlackBerry 10 will remember the last profile that you used and start using this as the toggle option.
Check out the screenshots below and don’t forget to check which profile you activate if you change them often!
Firstly, you can see that my profile in the settings is set to 'Normal'. Tapping the notification icon changes it to 'All Alerts Off'