Advanced way is to override this file in your custom plugin.

(You can start with this skeleton plugin.)

Create a new folder 'assets' in your data directory.

Put your logo to this folder, e.g.:

assets/topbar_logo.png

Copy the mentioned file to your custom plugin and change code on:

$asset_src = elgg_get_simplecache_url('assets/topbar_logo.png');


$logo = elgg_format_element('img', [
    'src' => $asset_src,
    'alt' => elgg_get_site_entity()->getDisplayName(),
]);


echo elgg_format_element('div', [
    'class' => 'elgg-heading-site'
], elgg_view('output/url', [
    'text' => $logo,
    'href' => elgg_get_site_entity()->getURL(),
    'title' => elgg_get_site_entity()->getDisplayName(),
]));

Thanks Nikolai,

It's very hard, but i will try