Open /etc/default/grub with sudo permissions with nano or vim or vi or what ever is your favorite editor.
Open the terminal
$ export $EDITOR="your favorite editor"
$ echo $EDITOR --> to check that the editor is properly set
$ sudoedit /etc/default/grub --> it will prompt you for your password write it and hit enter
Now add in the line
GRUB_CMDLINE_LINUX_DEFAULT = " quiet apparmor=1 security=apparmor ..."
Save the file
$ sudo update-grub --> it will prompt you for your password write it and hit enter
Restart your pc / laptop
