Login to Matomo (Piwik), in the top menu click on “Administration” and in “Personal > Settings”: you may select the website to load by default under “Report to load by default”.

Each user can specify which websites should be loaded in Matomo. Alternatively, users can choose to load the All websites dashboard, which gives an overview of the status and evolution of all websites available to the user.

Previous FAQ: How do I change the default language of the Matomo UI for all user accounts?