Reports are used to separate your feedback data (forms, data imports, etc) and dashboards. For example, you can set up a report for your sales funnels, your My account section on the website, the support section, different landing pages, etc. You can also use different reports if you have multiple websites or languages where you want to keep feedback separated.
Do you not know how to create new reports yet? Please read How to create a new report first.
You can now switch between organisations and reports:
Just click on the button next to the date range button, in the top right corner:
Choose a report - if there are multiple reports listed.
Note: users on "enterprise packages" are also able to switch between organisations and user roles. For starter and growth packages you are only able to switch between reports and to use the date picker.