In order to switch user accounts, choose in the main menu: File -> Switch User.
The login dialog will be displayed:

Here the user must enter his nickname and a password.
If login was successful, the program interface will be switched to the relevant account. In admin account, all existing controls, settings and buttons will be visible. And in Standard account, the most of the interface is hidden:

Then the application is launched, it automatically logs into the last active user account, so user does not have to enter a nickname and a password every time.