How to stop Skype from starting automatically? I close the Skype app in my Android phone (samsung s3 mini)

If Skype is open on my pc and I receive a call it also starts automacically in my phone without my input! 

How can I avoid such a strange behavior?
Thank you
Are you sure that you really closed Skype (not only hide it to background) ? In Skype main menu press "menu" button and then - logout. 

If that doesn't solve your problem I see two possibilities : 


Install a firewall (a good firewall is in avast! Mobile Security) and block access to newtork for Skype, unlock it only when you're using it (installing firewall requires root access)
Try to kill Skype service in application manager->background processes (it is located in Settings)


If you're true I think it is a bug and we've to contact Microsoft...