How to change post page title

You can add this to your functions.php.

/**
 *	Remove the word 'protected' or 'private' from post titles with passwords
 */
function the_title_trim($title) {
	$title = attribute_escape($title);
	$findthese = array(
		'#Protected:#',
		'#Private:#'
	);
	$replacewith = array(
		'', // What to replace "Protected:" with
		'' // What to replace "Private:" with
	);
	$title = preg_replace($findthese, $replacewith, $title);
	return $title;
}
add_filter('the_title', 'the_title_trim');

Hmm, I have it working on my site. Try commenting out ( add // in front of) the last line.
//add_filter('the_title', 'the_title_trim');

Do you still get the same error?

You should create a child theme before you start modifying the code. In your case you just need a style sheet and a functions.php file. then you can add support for menus to your functions.php file, and away you go. It’s not very difficult.

The way you’re doing it is too complicated and you’re messing up your original theme.

http://codex.wordpress.org/Child_Themes

I might also suggest that if your theme doesn’t support menus, it might be time to upgrade.

There is some error in your functions.php. It is tough to diagnose without seeing your functions.php.

As a rule of thumb, you if have more than ten lines of code please use pastebin to post it. Instructions here.
http://codex.wordpress.org/Forum_Welcome#Posting_Code

Second, I don’t see any obvious problems with the code other than it is using two deprecated functions. My best guess is your editor has added extra white space at the end of the file. Take a look at this help document and see if you can’t work through it.

http://codex.wordpress.org/FAQ_Troubleshooting#How_do_I_solve_the_Headers_already_sent_warning_problem.3F