Under the SaaS shared-responsibility model, what does the customer mainly manage?

In the Software as a Service (SaaS) shared-responsibility model, the cloud provider manages the underlying infrastructure, operating systems, and applications, including patching and middleware updates. The customer's primary responsibility shifts to managing user access, configuring application settings, and ensuring the security and integrity of their data within the application. Securing the physical server is a responsibility of the cloud provider in all cloud service models (IaaS, PaaS, SaaS).