Steps to follow to stop Background running apps in android mobile.
1.) First of all you need to root your Android Device.
2.) Install Titanium Backup * Root after rooting.
3.) Goto "Backup/Restore" tab and select app which is frequently running in background(say facebook, youtube, gmail, google play etc).
4.) After clicking on an app a Dialog box will be opened. Select freeze option.
5.) Now the application will not run in background.
6.) Inorder to use freezed app goto titanium backup>Backup/Restore>select app>Defrost.
7.) Helpful for slow devices.