In builder 4 the dashboard customisation has moved from being a globally defined property in theme administration to becoming a layout resource called dashboard.wiki associated with the layout itself.

This allows you to define several different dashboards, one for each layout if required - this is handy when you want to show something simple to anonymous/general users and something more advanced to other users.

You can use the tool on the backup tab to reimport your old dashboard data - this will copy the contents of your builder 3.x dashboard data to dashboard.wiki text resources attached to your root level layouts. Alternatively you can install an older version of builder & copy/paste the content out of the old tab.