My initial reply was brief because the question was so general. I agree that
locking the control would leave it easier to read than disabling it, but in
either case another option would be code in the form's Current event along
the lines of:
If Me.NewRecord Then
Me.DispatchControl.Locked = False
Else
Me.DispatchControl.Locked = True
End If
There should probably be a way of editing the original record if need be.
Sometimes I will set a label's double click event to unlock a control (or
whatever is needed). It depends on whether the point of locking the controls
is to guard against casual or accidental changes, or if the security needs go
deeper than that.