I have ubuntu 13.04 and kernel 3.11.

When I press e key at grub bootmenu I see the read only ro option at root partition and when I start system with that option I have low resolution and other problems.
Otherwise removing ro option before starting the system makes everything work fine.

I would like to know how to permanently remove ro option.
I have already checked /etc/default/grub but there is no ro, here is my grub:

GRUB_TIMEOUT="10"

GRUB_DISTRIBUTOR="`lsb_release -i -s 2> /dev/null || echo Debian`"

GRUB_HIDDEN_TIMEOUT_QUIET="true"

GRUB_DEFAULT=saved

GRUB_GFXMODE=1920x1080

GRUB_SAVEDEFAULT=false

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

GRUB_CMDLINE_LINUX=""

How can I do that? What file do we see when using e key at grub bootmenu? If I know that maybe I'll be able to edit it.

Thanks