Where to define GRUB_DEFAULT

[Helmut Schneider]

Hi,

where do I define GRUB_DEFAULT? /etc/default/grub sounds like "this is
the defaults, change it somewhere else". I read somewhere about
/etc/defaults/grub.d/ which does not exist. /etc/grub.d/ esists but
seems to be something else.

So where would I specify e.g. GRUB_DEFAULT?

Thank you!