For the timesheets which are in saved state before you update the billing rates, will affect when you click on save once again for already saved timesheet after updating the billing rates.

For the submitted/approved timesheets between the range of billing dates you updated will affect only when you enable the button called “Update all records within this range” and update the billing rate. So that timesheet which are in submitted/approved state will change the billing rates within this history date.

Go to Employee Edit (Employees–>Edit)

Select the Billing module in the Employee detail page where you find the Rate Histroy button, click on Rate History. Please refer below screenshot.

Click on Rate History will displays you the grid of billing rates click on edit option on the newly added billing rate as shown in below screenshot.

Once you done with this process the submitted/approved timesheet within the rate history will change the billing rates from old value to new value.