Change filter on a Tab
Select a Tab on which a filter is to be changed.
Right-click the selected Tab on a Tab Bar.
Select Change filter criteria on drop-down menu.
Click the Filter button on the Customize View form.
Check the Edit these criteria directly box on the SQL tab.
Change filter setting on the other tabs (e.g. Messages, More Choices, Advanced) of email folders:
Note: If you are an advanced user, you can change filter settings directly on SQL form.