Mail and Calendar default application

They also turn on and off with the click of only one button.
Why there's two buttons then? I do not know!

Brink said:

Please go ahead and post a screenshot showing what you see in Settings in Systems -> Default apps.

settings default is as below


control panel default for Calendar is as follows.

Brink said:

lvgandhi,

When you click on "Choose a default" for Email in your top screenshot, click on Mail if listed. If not, click on "Look for an app in the Store" to see if you can select the "Mail and Calendar" app there.

I can select mail. Problem for selecting from store is that link takes you to store. Mail and Calendar is listed as installed. But there I can not find a way to select it as default. Am I missing something. Same case for calendar default selection from store.