Optimizing images doesn't seem to be working

Hi, I have been looking at Pagespeed Insights the past week. Yesterday I had the score of something like 67 for mobile and 83 for desktop. I went back on it today and now I’m getting 67 for mobile but 34 for desktop… I don’t understand why my desktop has suddenly dropped. So I downloaded the new optimized images it provided and uploaded them via FTP but I’m still getting the error. I double checked that all my images are smushed with WP Smush Pro and it seems to be all done. The images that it recommends I optimize are the ones in the slideshow on the top of my homepage and a couple of the thumbnails of the blog post links available (which I can’t change as it will then affect the look of the thumbnails of those posts in the main blog page). Any advice at all please? Website here. Thanks.