You can set the basic rate formula individually or in bulk as follows:
Individual assignment
Go to the Payroll module, Pay Detail, search for the employee.
Click the Pay Calculation tab.
Change the Base Rate of Pay or Gross Rate of Pay.
Click Save.
Bulk or mass assignment
Go to the Payroll module, click Setup, and select Global Change.
Select Base Day Rate Formula under the Base Rate of Pay.
Select Base Day Rate Formula in the drop-down list under the General tab and click Next.
Assign Employee to All and click Confirm