In case you want to change the default word “Search” in the Search Button, into something different, this snippet will allow to change it.

Changing the search string in WordPress search form

/*/
/* Change Search Button Text
/*/

add_filter('get_search_form', 'my_search_form');
 
function my_search_form($text) {
     $text = str_replace('value="Search"', 'value="ok"', $text); //set as value the text you want
     return $text;
}