Why does creating a Payslip affects profit and loss statement in both Cash and Accrual Report
Because by design accrual accounting is used for payslips in both cases.
There are more differences between accrual and cash basis accounting than just whether money is paid or received. The timing of entries is also important. Switching between accrual and cash basis accounting really entails changing philosophies about when to record transactions. Manager (and other accounting programs) can only handle changes to the reporting aspects related to accounts receivable and payable.
Under accrual basis accounting, payslips should be entered when the obligation to pay an employee is created. That means you should enter the payslip during the accounting period when work is performed. Accrual basis accounting represents your true financial position, including the amounts you owe to your employees.
Under cash basis accounting, you should only enter the payslip when the employee is paid. Your obligation to pay employees at a future payroll date is not relevant. Thus, cash basis accounting presents a more limited view of your financial position. It really only describes your cash flow.
So you cannot switch between accrual and cash basis accounting without changing your transaction recording practices and expect correct results.