Can't seem to change difficulty level

[quatrozero]

Guys. Hello everyone. Did not ever think so many people would like this game like I do. Brilliant.

Probably just me being thick, don't all say yes!, but I can't get out of the arcade mode for some reason.
Doesn't let me do it on my PS3 but had no trouble with the demo....
Done all the Campaigns. Done all the single missions.

Come on all you aces. What have I done wrong or what have I not done at all? Some one must know. Would appreciate a little help.
Lost the booklet as well....Ho hum.

TO THE SKIES!!