Bookmarking a page on a previous computer, I used to be able to select Choose and all of my folders would appear everything is imported but the folders now do not appear under choose; help please

I recently got a new computer, downloaded Firefox and imported all of my bookmarks and bookmark folders from my old computer. All of my folders appear under Bookmarks. But previously when I wanted to bookmark a page to a specific folder, I could select "Choose" and all of my folders would appear under Choose, allowing me to select the preferred folder. Now they do not appear under choose. How do I get them to appear as they do on my old computer?