Modifying your page title improve the visibility of your website by search engines. Here's how you can customize it in your Page settings.
1. Navigate to the Website menu.
2. Click on Pages... link.
3. From the list of your website pages, choose the one you plan to edit and click on the Gear icon to open Page settings.
4. When you click on the Gear icon, a new window opens up. Here you can edit the Page title the way it will be seen in search results.
The average length of page titles in search results is currently 83 characters, however, the optimal page title is 55 characters which should display your title in full on most devices without truncating.
You can read more about Page settings in this tutorial.