Change Login Form Labels

functions.php

/*////////////////////////////////////////////////
 //
 //	Change login form label
 //
 ////////////////////////////////////////////////*/

function gettext_filter($translation, $orig, $domain) {
    switch($orig) {
        case 'Username or Email Address':
            $translation = "Melon Username";
            break;
        case 'Username':
            $translation = "Melon Username";
            break;
    }
    return $translation;
}
add_filter('gettext', 'gettext_filter', 10, 3);