How to modify the add node forms using hook_form_alter
See below code which works.. Form element is title instead of edit-title.. print $form array to investigate form elements...

function MYTHEME_form_alter(&amp;$form, &amp;$form_state, $form_id){
switch ($form_id){
    case "q_a_node_form":
        $form['title']['#size'] = 10;          
        break;
    }
}


If you have installed devel module you can see elements using below code

dpm($form);