[AccessD] Changing Combo Box Data Source

I know there is a way to do this.  Where are the Friday Jokes?  My form
opens.  The combo box on the form is filtering for only "Open" items.
However, PIA user wants the option to see all projects, open and closed.
What code do I throw on a button to change the record source of the
combo box to take off the filter?  Is it setting the recordset?  Thanks.