• Change $CONFIG->wwwroot in /elgg-config/settings.php
• Change main URL via Settings : Advanced Settings - System - The site URL 
• Flush the caches / Upgrade
• Empty any activated CDN caches (if it exists)

Note: Use Google to learn how to configure Apache with SSL (e.g. 1, 2, 3)

And keep in your mind some https enabling problems also:

• https://smallbiztrends.com/2015/04/changing-from-http-to-https.html
• https://css-tricks.com/moving-to-https-on-wordpress/
• https://www.seo.com/blog/seo-tips/3-common-url-problems-and-how-to-fix-them/
• https://elgg.org/discussion/view/1658874/https-issue-https-shortcut-link-is-not-working
• https://elgg.org/discussion/view/1442318/https-works-fine-but-homepage-graphics-are-gone

Read this also.

It's also helpful to add some rewrite rules to the .htaccess file to get forwarding from non-ssl to ssl site url (and non-www to www or vice-versa). I have these rules - but they are for Elgg 2 and I've not tested them on Elgg 3 yet.

# If you must add RewriteRules to change hostname, add them directly below (above all the others)

# http to https
# exclude subdomains
RewriteCond %{HTTP_HOST} ^(www\.)?YOURSITE\.URL$ [NC]
RewriteCond %{HTTPS} off
RewriteRule ^ https://www.YOURSITE.URL%{REQUEST_URI} [NC,L,R]
# add www on ssl
RewriteCond %{HTTPS} on
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^ https://www.%{HTTP_HOST}%{REQUEST_URI} [NC,L,R]

These lines are added after the

# If you must add RewriteRules to change hostname, add them directly below (above all the others)

comment line. The rules are for forwarding any non-https calls to the site to the https url and assume that your site url contains www (without www you would have to have slightly different rules to forward from www to the non-www site url). You would have to modify the YOURSITE.URL parts to match the url of your site

These rules help for any links (either on your site itself for example in a comment on some other posting referring to some other page or if a user bookmarked the site) to get them always moved to the correct https urls.

I can't get my new SSL certificate to work. The fight was hard but Mr,SSL has won me by far, I give up. I do not have enough knowledge to put it into operation. I'm a noob! :(

Thanks in all ways RvR and iionly.

You can't use `order_by_metadata` with more than 1 field. If you wish to order by more fields use `$options['order_by']`, this can accept an array of order fields (make sure they are in the select)

Look at this.

Thanks a lot

of course, the sum_of_metadata_a and the sum_of_metadata_b are for the Parent_guid of the record :)

Play with this

Very useful

Thank you very much for your help