Rustler is right. For now, there isn't a detailed report specifically for users' activities (that includes what accounts they were accessing, reports viewed, etc.). This is a great product suggestion though. I'll surely pass along this to our engineers so they may consider it adding in our future updates.
In the meantime, you may use the Audit Trail report available in QuickBooks Desktop. To learn more about it, please see this article: The Audit Log: What it is, how to use it.
Please don't hesitate to post more questions. Have a nice day!