Found a bug I think.

1) Enter E-mail to paypal address in the profile page
2) Click Update paypal button.
3) Enter a different E-mail address in the paypal address box.
4) Click Update Paypal button
5) Box reverts to the first e-mail entered and does not update.

Least, that's whats happening to me.

Edit: Logged out, logged back in, tried again to change it... same thing.