Scrivener not showing annotations/comments from external editor

Hi, I am a newbie, and have been trying to annotate/highlight PDFs. I import them into my research folder, then I open the PDF I want to annotate or highlight in an external editor (Acrobat). I go back to Scrivener but the PDF does not show the changes I’ve made in the external editor. Also, if I want to save the changes on the PDF, I have to save the PDF as a new file, which is confusing as well.