When there are different tenants on the same server, you can add different logos for each one. The attribute tenantId is stored in the session.
The default tenantId is /pentaho/tenant0. The Change Me! logo image is stored in /pentaho-server/pentaho-solutions/system/pentaho-interactive-reporting/resources/images/pentaho/tenant0 with the nameLogo.png. When you have multiple tenants, each tenant is represented by a folder with a unique tenantId in place of "tenant0". Each tenant folder must contain the logo of the respective tenant named Logo.png.