webmail notifier

Hello,

I use portables applications on an usb-disk.
I would use webmail-notifier ( a firefox extension ) for check my mail on differents mailboxes. No problem for installation, when Firefox start, webmail-notifier is also running, the problem is that when You make settings for your mailboxes, I suppose a file containing mailboxname/login/password is created but not stored on the USB-HD.
This setting must be created every time and this is not very usefull...
How to do for keep informations on the USB-HD ?

Thanks to everybody...