Open your FTP.
public_html/wp-content/plugins/wp-pro-quiz/lib/view
Goto
> wp-content
> Plugins
> WP-pro-quiz
> Lib
> view
> WpProQuiz_View_FrontQuiz.php
Ctrl + F to find the button text you are looking for. Sometimes its case sensitive. You can edit any button text from the file. May it be Start Quiz, Finish Quiz, Results, Restart Quiz or any text you see on the plugin published page.
