In order to create a custom dashboard or make changes to the overview page you will need to enter ‘editing mode’
Go to the overview page and look for the three horizontal dots in the top right corner and click:
If you do not see the above options in the dropdown then you don’t have sufficient privileges to edit the overview page.
Once you switch editing mode on you notice lots of options for cards, columns and sections now appear. You can edit and change what you like, once happy press save changes and your settings will apply across all users.