I'm sharing this simple tip because many people don't know about it. Are you the type that has many applications with similar functions? Do you love to choose the one you want among these applications whenever you need that particular function?

Here is an example: you have 3 different launchers on your phone, and love the freedom to choose whichever one you want among them when you tap the home button. By mistake, you made one of these launchers your default launcher (i.e. by clicking "always" instead of "just once". This step should be applied if you do not wish to reset all your apps preferences.

The following are the simple steps​ to restore that freedom to choose among different applications that serve a similar purpose:

(1) Go to Settings => Applications (Manager) => Locate the app you just made default, or that which has always been on Default.

(2) Click on the app, scroll down on its information and you will see "Clear defaults".


source: http://bbs.tecno-mobile.com/forum/general/100260-how-to-undo-a-default-application%E2%80%8B