I want to change default Desktop environment from GNome to KDE.

My asking is for CentOS 7, I was Trying with 

https://unix.stackexchange.com/questions/181503/how-to-install-desktop-environments-on-centos-7

 # echo "exec startkde" >> ~/.xinitrc
 # startx

Efectively KDE Environments Starts


But, Restarting, Again I have Gnome.

I want Restarting starting with KDE.

**Where I can change deafult Desktop Environment?**

PD. Solution for CentOS 6.x doesn't work!