How to change default app in Windows 10In Windows 10 there is a separate "Default App Settings" to manage default apps for various purpose.
Just open start menu and search "default app" and open "Default app settings" (system settings).
Now you can see five main categories for default apps and in case if you need to choose default apps by file scroll down and click on "choose default apps by file type". To change default apps for different protocol click on "choose default apps by protocol".
How to change default apps in Windows 7
There is a desktop app to change default app in Windows 7, this default app is available since Windows vista and can be accessed from control panel. Windows has just changed user interface since Windows Vista and all other settings do exists in control panel and Windows setting dashboard in Windows 8, 8.1 and Windows 10. Just navigate to following path :-
Control Panel\Programs\Default Programs
Choose "Set your default program" option and proceed.