How to export as a root user on RHEL7

 [sam@master ~]$ xhost +

[sam@master ~]$ xauth list

[sam@master ~]$ echo $DISPLAY

[sam@master ~]$ sudo su -

[root@master ~]# xauth list

[root@master ~]# xauth list server:  MIT ..cookie.. dd2....

[root@master ~]# xauth list

[root@master ~]# firefox http://mywebsite.com