Important: Before making any changes, back up your WordPress installation. If your host uses Softaculous, you should be able to create a backup right through the Softaculous area in your cPanel. Otherwise, the backup will need to be done via phpMyAdmin (click here for phpMyAdmin database backup instructions)
To update your sites URL to reflect https, first update the site URL in Settings >> General (note: you may need to log back in afterwards)
Next, we will install the plugin Better Search Replace.
Go to Plugins and then click Add New at the top and search for “Better Find Replace”
In this case, I have it installed already so it shows as “Active”. You will need to click “Install”, and once installed, click “Activate”.
Once Installed, click on the “Tools” menu, then on “Better Search Replace”
Here, you will enter the current url in the “Search for” field and the new url in the “Replace with” field, then make sure all tables are highlighted (see example below)
Make sure to keep “Run as dry run” selected and click “Run Search/Replace”
Once you click “Run Search/Replace”, you will see the search progress below
Once the Dry run is complete, along the top the number of updated needed will show up
Remove the “Dry Run” checkmark and run again to make the changes.
Once the updates complete, something similar to the details below will show up
This should be all you need to do. If your site still shows insecurely, you can run a scan at https://www.whynopadlock.com/
If it shows that “Force HTTPS” is not enabled, you can enable by following instructions here: How to force SSL with .htaccess
If you are using an older theme, there might be theme related or google related permalinks that are next to impossible to find. In these cases, I’ve been using the “SSL Insecure Content Fixer” plugin, which is a quick and easy fix and allows the site to load securely.