How to Fix Website is Not Secure Browser Message?

Why does my website say it’s not secure?
Any modern browser will display the “Not secure” warning in the address bar when your website is using HTTP instead of HTTPS.

An SSL certificate can be used to encrypt and decrypt data transferred to and from your website.
The best way to deal with the question “Why does my website say not secure?” is to install (activate) an SSL certificate.
Install Your Free SSL Certificates with just one Click in our ControlPanel, or alternatively You can order a paid certificate.

Step 1: Install a free SSL certificate
– Login to Your ControlPanel and navigate to the Domains page
– click Let’s Encrypt from left menu
– click the activate button
– your website can now using a secure connection via https:// instead of http://

Step 2: Update the URL in your website configuration

For WordPress
First, you need to visit Settings > General page. From here you need to update your WordPress and site URL address fields by replacing http with https.

Don’t forget to click on the Save changes button to store your settings.

For Joomla see:
https://docs.joomla.org/Enabling_HTTPS_on_your_site

own PHP or HTTP Websites
create a .htaccess file or add following code in your existing .htaccess:
RewriteEngine On
RewriteCond %{SERVER_PORT} 80
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

If you still see a warning because of unsafe content please read:
https://managewp.com/wordpress-ssl-settings-and-how-to-resolve-mixed-content-warnings

https://blog.sucuri.net/2016/04/troubleshooting-mixed-content-warnings-https.html