In order to backup your bookmarks so that they can be retrieved if ever lost or deleted first go to the 3 dots at the top right corner of the screen (next to the star!)
Under the bookmarks tab open the Bookmark manager page
Once under the bookmark manager page simply click the 3 dots again for options and export bookmarks as pictured.
Choose the name of the file and where to save it to finish.
In order to retrieve your bookmarks simply repeat this steps and select import to import the bookmarks into your browser.