VB 2010 OleDb - How To Update Specific Row

I have login system where once logged in, there is a global variable which holds the users ID. In another form, I have an SQL update which updates rows in the user table. So my dilemma is this: When I try to update it either updates the first user only, or all users.

The SQL I have :
Dim Update As String = _
"Update User Set field1=?, field2=? field3=?"

What I would like is...
Dim Update As String = _
"Update User Set field1=?, field2=? field3=? where ID =?"
However this doesn't work.