It's not on your PC. Goto amazon, click "Your account" at the top, then you'll notice "Your Account Settings," with "Access or change your 1-Click settings."
This helps because just about everybody buying a PS2 in the 30-90sec window it's available is using 1-click buying. I'd be careful though, the 1-click thing is basically an auto-checkout with no login/pass reqiured...so you wouldn't want it on all the time if you're using a public computer or if you have "evil" roommates (like mine), for example.
It's pretty easy to turn on/off after you configure it, though, so no sweat.
Hope this helps!
-d