In WATS, the default start page is a standard Dashboard view. You can change this to whatever report or custom dashboard makes the most sense to you to look at first.
If you would like to start with a custom dashboard, make sure to create the dashboard first and assign it as your favorite. See the article Setting Up Your First Dashboards for more information on this.
After logging in to WATS, select the icon showing your initials in the upper right corner, then select My Settings
Under Theme and Homepage you can make your selection.