The default screen options are saved in wp_usermeta the meta_key is metaboxhidden_post. 

I think the easiest way to set default options (or to hide specific boxes) would be to use a plugin like adminimize. I personally use the advanced custom fields plugin for this task (and a lot more).

How to change Default Screen Options in Wordpress
I was reading the untap step rule and got confused a bit. It says:


  502.2. Second, the active player determines which permanents he or she controls will untap. Then he or she untaps them all simultaneously.
  This turn-based action doesn't use the stack. Normally, all of a
  player's permanents untap, but effects can keep one or more of a
  player's permanents from untapping.


If "a player determines", can I determine not to untap all my permanents?
