No one has the liberty to change the authors composition without licence no matter the reason

I am not sure what "without licence" means. If you mean "permission" - are you saying it can't be done even if the author is dead?

And how - pray - is the author going to stop them even if alive? And what if the author approves of the change?

And does that mean it has to be sung in its entirety. And what if you forget a verse? Does that mean you can't finish it?

And what if the change is done by a mishearing? Does that still count?