When a global or SharePoint administrator creates a hub site, they're essentially converting an existing SharePoint site to a hub site. Once they've done the conversion, the hub site owner can take additional steps to apply common navigation and branding across all associated sites and to help users discover related content such as news and other site activities.
You must be the site owner to perform these steps.
Some functionality is introduced gradually to organizations that have set up the targeted release options in Office 365. This means that you may not yet see this feature or it may look different than what is described in the help articles.
Steps to get the most out of your hub site
Change the hub site name and logo
To edit the hub site name and logo, go to the site, click Settings , and then click Hub site information. The logo height should be no more than 24 pixels.
The name and logo will appear in both the hub site navigation bar and when users associate sites with the hub.
Edit the navigation bar
You can also edit the hub site navigation bar that appears on all associated sites.
Change the hub site theme
To set the hub site theme, click Settings , and then click Change the look.
All sites associated with the hub site will inherit the theme from this site. Note that it may take a while for the theme to be applied.
If the theme for the site that was converted to a hub site was never changed from the original theme assigned by SharePoint at the time it was created, any sites associated with it will not inherit the hub site theme.
Classic experience SharePoint sites that are associated with a hub site will retain their original theme.
Add the News web part
Add the News web part to the homepage (if it's not already there) to see news from associated sites. On the web part properties, select "sites across the hub" as the source. You can choose which associated sites display news on the hub site home page and users will only see news for sites they have access to.
Add the Sites web part
Add the sites web part to the homepage to see activity on associated sites
Add the Highlighted Content web part
Optionally, add the highlighted content web part to see spotlighted content from associated sites.