SSL problem while editing page

Hi,
Please note that I am experiencing this issue all the time as my websitessomehow become “Not Secured” for some reason even when a valid SSLcertificate (Lets Encrypt) is installed on them. Furthermore, my WordPress URL and Site Addresses are grayed out in WP General Setting therefore I cannot change it HTTP to HTTPS.

When I submitted the above issue to the Bitnami Community (Wordrpess) they sent me the link (https://docs.bitnami.com/aws/apps/wordpress/administration/configure-domain/) and recommended to make following changes in Cobfug file:

Configure The WordPress Domain Name
If you are using WordPress v3.3.1-5 or higher, only specify your domain name in the /opt/bitnami/apps/wordpress/htdocs/wp-config.php file. Edit and replace the following lines as shown, remembering to replace the DOMAIN placeholder with the actual domain name you wish to use:

define(‘WP_SITEURL’, ‘http://’ . $_SERVER[‘HTTP_HOST’] . ‘/’);
define(‘WP_HOME’, ‘http://’ . $_SERVER[‘HTTP_HOST’] . ‘/’);

with

define(‘WP_SITEURL’, ‘http://DOMAIN/’);
define(‘WP_HOME’, ‘http://DOMAIN/’);

I deleted the original lines and replaced them with the new ones as instructed and press Ctrl+X followed by “Y” to save it and closed the session. When I open a SSH session again, the two original lines were still there, while new ones were not.
It seems the they never got saved.

Your assistance required please.

Rregards