I am a Singer, Song-writer/ Producer of my own original music... Now If I post my Original work on YouTube or Vevo is it considered viable proof that the music is truly my own original work; is it proof to my own copyright?

I am aware that as soon as the idea is thought of and conceived; put on paper or stored in computer data that it is copyrighted. However is all this proof enough for me to be able to sue if my work or part of my work is stolen and used to make profit without my permission? Can I sue if someone else legally copyrights my works before I do?