You can call your song anything you want. You can use a word or phrase that’s in the song… or just take something you like seeing at the top of the lyric page or sheet music and name it that. Your call.
But the real title is the word or phrase that the listener is going to take away with them; what they’ll most naturally remember; what you repeat. In other words, the central lyric idea of the song. Most (not all) well-written songs are title-based; it’s always been that way.
I often work with writers who aren’t sure what to name their song, and then offer several options, usually taken from their lyric. To me, this question almost always points to a problem with the song, not the title (or, less commonly, that the writer just doesn’t yet realize that they already have a title staring them in the face – or ear).
Most of the time I don’t think we need to be worrying about what to ‘call’ our songs. The title should be obvious when you listen to the song. If it’s not, that’s the problem – what needs to be addressed is probably a lack of clarity in the writing … ‘choosing a title’ is usually a completely secondary issue.
The centrality of the title should present itself… not necessarily obviously, but clearly and unambiguously. For titles that present themselves this way think of ‘Happy’, ‘You’ve Got To Hide Your Love Away’, ‘Rock Steady’, ‘Stayin’ Alive’, ‘I’m So Lonesome I Could Cry’, ‘Hallelujah’… on and on and on and on… millions of other songs. You do not have to look at the lyrics to know what the title is. And this isn’t pandering. The songwriter is just taking full advantage of what may be the most powerful tool in the songwriters’ kit – having a strong central idea (which also includes the melody of the title).
Songwriters don’t have to do this, of course. There are many ways to construct a song; I’m just talking about the most common. There are numerous great songs with a title that isn’t in the lyric of the song, such as ‘The Christmas Song’ (‘Chestnuts roasting on an open fire…’), ‘A Day On The Life’, ‘Smells Like Teen Spirit’, many early songs by Bob Dylan and those influenced by him (after his early days Dylan ended being a Title guy), Iron & Wine’s ‘The Trapeze Swinger’ (I wrote about that one here). But all of these songs have great, immediately memorable themes of different sorts.
A title’s presence can also be subtle and insinuating: think Paul Simon’s The Boxer ‘or Eric Church’s ‘Springsteen’ (Bruce Springsteen himself, after his first few albums, has, like Dylan, tended to focus strongly on titles).
Another exception worth considering is the song that is so hooky that it has more than one possible natural title. An example would be ‘Single Ladies (Put A Ring On It)’… the title could be either one of those phrases (and then there’s a third hook: ‘Uh Uh Oh, Uh Uh Oh…’). It’s hard to get too much of a good thing.
Anyway, in most cases the song itself will (and should) tell you what the real title is. It’s in the writing, not in the titleing. You can put anything you want on the top of the page.