Sub-total hours is incorrect.

Hi,

The associate who is regular working got the incorrect sub-total calculation in hours. when I go to Navigator >> Receivable >> Billing  from Task I select "Manage Transaction" and I enter the Transaction number/ invoice number and then click on Search, when I open that invoice in "View Image" I can see the Sub-total working Hours is 40.hours instead of 200.hours because the person worked for 25 days for 8.hours. and the sub-total Amount calculation is correct only Sub-total Hours is incorrect

How to correct the associate working hours. Can someone tell me steps by steps process, so I can correct the working hours.