WPBakery Visual Composer

Hi, I can’t change the content of my pages because I see nothing; if I change to “classic mode” I can see the code of visual composer, but is very difficult change it. How can I do? I can’t update the theme and I think that is very dangerous update only the latest versione of plugin. I absolutely don’t want to lose anything. I have the latest version of wordpress and plugin classic editor. Please tell me something!