1. Related to this discussion: make this:

if(elgg_in_context('index') || elgg_in_context('main')) {
  $navbar = elgg_view('page/elements/navbar', $vars);
}

In your copy of mod\aalborg_theme\views\default\page\default.php

2. Copy this file vendor\elgg\elgg\views\default\page\elements\sidebar.php to mod\your_theme\views\default\page\elements\sidebar.php

Now edit it:

<?php

echo elgg_view_menu('extras', array(
    'sort_by' => 'priority',
    'class' => 'elgg-menu-hz',
));

if(!elgg_in_context('activity')) {
  echo elgg_view('page/elements/owner_block', $vars);
}

echo elgg_view_menu('page', array('sort_by' => 'name'));

if (isset($vars['sidebar'])) {
    echo $vars['sidebar'];
}

Read the docs

SOS!

Would the River Addon plugin (https://elgg.org/plugins/825625) be an alternative to the 3-column river activity plugin?

If the re-arraning fails, the plugin might have a bug or the plugin just can't offer the exact layout you are looking for. Then it would be necessary to fix the code or to modify the plugin to get the result you want.

Did you mean, only these lines should work? I have tried, no luck!

Again,

create your own views\default\page\default.php (for example, copy it from aalborg_theme mod to mod\your_theme_name_here\views\default\page\default.php)

Now try this code: just copy-and-paste inside the file default.php

Thanks a million. It worked great.

I have a few more questions, if you have time, you may also like to see this, as its similar to what you have advised here. URL: https://elgg.org/discussion/view/2575084/how-to-stop-nav-bar-from-appearing-in-the-indexhome-page 

Search in Plugins: Chameleon, Custom Style, Customizr, Elggcss (galliCSS), enColor, Lee's Theme Designer, or just use Time Theme Pro.

Be sure that the plugins' versions are compatible with your Elgg.

Also Themer. But author dump it I think. Only enColor work Elgg 2 I think. And enColor change no logo unfortunate.

Thank you all. You input helped me to explore and finally to solve the problem. Appreciate it. Bests.

Can you open the JavaScript console and try it? I think F12 will open it. https://dev.windows.com/en-us/microsoft-edge/platform/documentation/f12-devtools-guide/console/

If this is a new site with only bundled plugins, feel free to create an issue: https://github.com/Elgg/Elgg/issues/new