Updates Access 2007

Hello,

I have to make updates to forms in a database not created by me, and I have
two problems with which I need help as follows:

There is a form with a key field, which will not allow me to update the
data, when I try I get a message to the effect " the changes you requested
would create a duplicate key". I have created such a form in other data
bases with no problem. I am missing something but can't see what ...

Another form in this data base shows a scroll bar across the screen in an
area which contains an array of totals. How can I see the fields behind the
scroll bars?

Any help with these problems would be most appreciated.

Abay