I published an article which I previoiusly posted on Researchgate as a pre-print. I was allowed to upload the printed version but the status remained "pre-print", and I cannot change it. Is it even possible?
This is not possible, you have to create a new page for the published version. For more details, see my replies to this identical question: https://www.researchgate.net/post/How_can_I_remove_the_word_preprint_in_an_article_and_change_it_by_article