How to I update the Array List from the DataGridView

I have a DataGridView bound to an Array List.  The grid displays the contents of the Array List perfectly

I would like to enter changes in the Grid and have them update the Array List items.  The Grid does not change the items when I do this.

What am I missing?  This works fine with a SQL database as the Data Source.  I need it to work in a similar fashion with an Array List.

MP