See how to find Windows 10 version you have installed. If you are running Windows 10 RTM, Windows 10 version 1511 or Windows 10 version 1607, you need to go to System - Defaults apps. To set default app associations in Windows 10, open Settings and go to Apps - Defaults Apps. There are different ways to assign an app to a file type. Here is how to choose default apps in Windows 10. The classic applet to change default apps has also been converted to a page in Settings.
Personalization, Network options, User Account management and many other options can be found there.
Starting with Windows 10, Microsoft moved plenty of classic options from the classic Control Panel to the Settings app.