Notification Bar on Xperia Z3 is where you can see your recent notifications as well as have access to quick toggle settings buttons, and of course see date and time.
To customize notification bar on Xperia Z3 do as follows:
1. Drop down the notification bar with 1 finger to see the current Notifications.
2. To see the quick settings, simply tap the Quick Settings tab on the top right (You may also use 2 fingers to slide down, when the notification panel is not open)
3. To customize the toggle buttons, tap the Edit button
4. Now to add a new quick settings button, find it at the bottom and simply drag and drop it to the main quick settings area at the top