I can not change this value, I establish zero but when you start your pc grub menu appears for 15 seconds until it self-select.
GRUB_DEFAULT=0
GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=0
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="splash intel_pstate=disable quiet"
GRUB_CMDLINE_LINUX=""
I do wrong?
$ lsb_release -r
Release: 14.10
sudo update-grub
afterwards to apply and save the changes you made?