If it keeps losing three hours all the time you change it, then you have to check the regional settings, and also ask it not to update automatically.
If that doesnt work, you need to have your CMOS battery changed, but if its the CMOS battery, it will always go back to the date the PC was made (not bought) and 00.00hrs
If it's losing time the battery has died.
Open the case and look for a small watch type battery.
Remove it and buy a new one.
Replace battery and the time should be OK