You will need a child theme to apply these changes.
The Child theme is needed to keep the changes intact in case you update/reinstall your Divi theme. To learn about it or get more info please check the following tutorial first: How To Make A Child Theme

To change the default order of the Divi Portfolio items (projects), you can add the following code to the functions.php file in your child theme folder:

// Order the portfolio items by title
add_action( 'parse_query', function( $vars ) {
if ( 'project' == $vars->query['post_type'] )
$vars->set( 'orderby', 'title' );
$vars->set( 'order', 'ASC' );
}); // end custom order

WordPress allows you to select a lot of order options. In the code above you can modify the following two lines to change the order method to something else:

$vars->set( 'orderby', 'title' );
$vars->set( 'order', 'ASC' );

You can find all of the available order parameters here:

The changes will affect all of your portfolio products. It's currently not possible to apply these changes only to a certain portfolio module. 

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