The total count of supporters and dollar amount to the right of your filters is calculating based off the filters you've applied.
To Access your Transaction Reporting:
In the Transactions section, add a filter by clicking "add filter".
2. Select the filters you want to apply by accessing the "select an item" drop down menu and click APPLY.
A few example segments you can easily create with filters:
Donations over $500
Donations today, this week, month, year