Some QuickBooks Desktop activities cannot be performed in multi-user mode because of the way the activities interact with a company data file.
The following QuickBooks Desktop activities can be performed in single-user mode only:
To change from multi-user mode to single-user mode, select the File menu and then click Switch to Single-user Mode.
Also, some functions within QuickBooks are lock out functions, which means that the first person to use such a function "locks out" other users from using that function at the same time. Two functions are Payroll and Online Banking.