Here's why:
* Quotation marks are used for titles of shorter works like songs, poems, articles, essays, speeches, and chapters.
* Italics are used for longer works like books, movies, plays, albums, and magazines.
* Underlining is an older style of emphasizing titles, and while it's still sometimes used, it's generally considered outdated.
So, if you're writing the title of a speech, use quotation marks:
"The Power of Words"
"Building a Better Future"
"The Importance of Education"