Some apps are automatically downloading and forcing me to install them.

[AC Question]

Once i tried to download an app from 9apps, that was not available on play store. when i downloaded it something happened and suddenly 9apps appear on my screen that wants my permission t install. i denied it then it was getting again and again and when i install it there is again an another app named Wifi internet speed. i dont want these app and when i try to uninstall these app these app these appear again. please help me how to stop download these apps in background and prevent to install

 

[belodion]

Is Unknown Sources enabled or disabled?