SEO by Yoast won't work when multiple page versions is stored?

Hi,

I’ve installed and activated WordPress SEO by Yoast and cannot seem to change or add anything to the Yoast tool located on the pages editing panel. I write for exampel a meta description and then update the page, but then the description disappears again. I’ve heard that SEO doesn’t work when the current page has several versions stored, and I like to erase old version but cannot find a way to do it i Fruitful. Anyone who can guide me?

Thanks