SSL http conversion to https not working on search.png

I converted to https from http using Search and Replace. It worked fine on another WordPress blog I have ([login to view URL]). When I did it on [login to view URL] it gave green padlocks for all pages. The search and replace as carried out by TSO Host. Everything worked. I hung up the phone and unpaused thiscureworks on Cloudflare (I had to pause to change the IP’s). After doing this unpausing on Cloudflare, the next day Firefox, Chrome etc keeps saying the file: [login to view URL] is being served through http instead of https. My web Host who use their feature called “Let’s Encrypt” wrote me: “I have checked your case with a colleague of mine who advised me that because the [login to view URL] URL still goes through http it might be included in some of the files of the website. When we do the search and replace, we search for the link only in the database of the website, we don’t go through the files.” Do you know if there is some kind of cache issue with this one particular [login to view URL] file? What makes no sense to me is that the [login to view URL] is in the header of all pages, so why dows the green padlock not show on the home page, the blog page? How I can get this [login to view URL] and blog page to conform to https?