I am not sure what you mean, but all passwords should switch to multitap. I have noticed on some browsers it switches to multitap to - until I scroll to insert symbol. Yes this is on BB other than storm, but I would think it would be the same for you.
Posted from my CrackBerry at wapforums.crackberry.com
Imho I believe its due to the fact that you are running a third party app like opera that is not specifically made for the storm. I know that when I didn't have opera installed running .90 I had no problem with the sure type changing. As soon as I use opera the switch happens. Try not using opera for a few days and you won't have to change. Also if you choose the full qwerty keyboard in portrait mode the switch won't happen either.