When running a report like the Profit and Loss report, it will provide you a total per line item for Total Expenses, Total Revenue, and GROSS PROFIT. Same with other reports, it will give you a total per account, items, customers, vendors, bank account, and others. If you are referring to adding the Total of all of them at the bottom of the report, then that option is unavailable in QuickBooks Oline (QBO).
What we can do is export the report to Excel and from there you can modify it to come up with the data you need. For more details about modifying reports, see the Customize reports in QuickBooks Online article. Feel free to visit our Reports page for more insights about managing your financial reports on your business.
You can also visit these blogs for any upcoming QuickBooks updates and enhancements: