Listening songs

I think I've improved my English because when I listen to songs or movies in English I can distinguish many words. But I have a question for those who know the language very well. When you hear music do you perfectly understand what the song says or do you have to read the lyrics letter to avoid confusion? I ask this because the English have has similar sounds, for example, used and just; the sounds seems the same. Also, when I search for song lyrics sometimes there are mistakes. For example in the song Madness of Muse I understand I need to love, but the lyrics read letter says I need your love.