Have you ever installed ssl on your server? Then and have unsecure errors? If you have a tough time trying to figure it out, what is not in https:// is giving you the warning. Most of the time if using wordpress it’s in the theme header.php from google fonts, sometimes its in your regular inbound and outbound links, remember to make it secure everything on the page must read HTTPS all links, If not that error will constantly pop up over and over again. Here is a site you can check why your website is unsecure, when your SSL Cert is properly installed. www.whynopadlock.com.
Hint to save extra money, You can buy a SSL CERT anywhere and install it on ANY SERVER, don’t let your hosting provider try and fool you, Godaddy is the most inexpensive way to get SSL Certs, I have found this out the hard way!