https://support.wix.com/en/article/corvid-tutorial-creating-a-show-more-link
If you are following that tutorial, then nothing should change when you click on the show more button.
Looking at your page layout, you might be better doing this sort of double collapse design from Nayeli (Code Queen) as shown here.
https://codequeen.wixsite.com/double-collapse
https://www.youtube.com/watch?v=HmTkf5af0NE