I read on gamewinners.com that when u enter the guild and the atom appears (the nice multicolour thing) the colour that u set it 2 becomes ur section id colour for the mission, is this true :S
dont think its true

I alway press a button on that screen an dmy id never change

It's a load of BS. Your character's ID never changes once it's been set.
lol. mimas is right, you absolutely cannot change Section ID after you create your character. That's why it's wise to figure out which ID/Name you want using the Section ID Calculators located everywhere, including right here on the site.
its just there for looks and something u can do while u r waiting
k thanx guys im gonna compalin to game winners about bogus info
