Every rule has its exceptions, setting drupal_set_title directly on form_alter doesn’t work for node form title. To customize pages like “Add node”, or “Edit node” :
Make a module
Add a function to implement hook_form_alter
Add a form afterbuild in your hook_form_alter implementation:
$form['#after_build'][] = '_my_callback_form_set_title'In
'_my_callback_form_set_title', usedrupal_set_titleto change the form title:drupal_set_title(...)Update system table to have the weight of your module greater than Node module (on a default install, core modules are weighted 0, so set your module weight to 1).
Rebuild registry, clear caches.