There is a default Operations Monitor.
You may not see which user entered which sheet from there. What you need is a sort of Governance Dashboard for Qlik Sense. But it is not available by default as far as I know. But you may open Audit Logs from Proxies--> Central-->Logging. Then you can find the Audit Logs in C:ProgramData\Qlik\Sense\Log\Proxy\Audit and check for the details you seek.
You can increase the verbosity from the same QMC screen.