SIte ignores style and image folders after upgrading Mac and app

I maintain a simple Dreamweaver site made by someone else quite a few years ago - I'm a graphic designer rather than a web designer but understand the very basics of code. I recently got a new Mac with a new OS, and reinstalled all the Adobe apps. When I went to update the website the local files (stored on Dropbox) opened blank and I had to download them from the live site - they looked unstyled but the design view never looks right anyway so I went ahead and updated in the code view as normal. Uploaded and all looked OK on my Mac and iphone. But someone else let me know that lots looked wrong on their various devices and browsers and I looked in an incognito window on my Mac and the style sheet wasn't being applied and all the new images weren't showing. Updated text was correct. I checked that the new images had gone into the image folder and that the stylesheet was in the styles folder, and that the paths were correct in the HTML. Older images which did show live were in the same images folder with the same paths. I also checked in the folders on the host server. The bodge I have done for now is to put the stylesheet and images in the same folder (public_html) as the HTML files and delete the folder names in the code and this works - but I would like to knwo what happened and whether I can restore the folders as the single folder I have now is a bit of a jumble sale. I assume it must be to do with something new in either the version of DW I downloaded (though it is 2021 and I always keep my Adobe programmes up to date) or the new Mac (mac mini with Ventura 13.6.1)?  Any ideas most welcome!