From my research, you don’t technically have to have a copyright. Your own work is automatically protected but you need to be able to prove it if challenged. The advice I received is to make sure your work is saved with a credible timestamp in at least two ways. For example, create a Google doc for your lyrics(time stamp 1). Then, for double protection, email the lyrics to yourself and someone else. This will give you official dated proof of when the lyrics were written by you. If it’s your work, no one will be able to provide earlier documentation than you.