How to install A3 USB driver on Windows 8.1 x64 or Windows 10 x64 ?A3 USB / ScanExpress A3 USB :This driver is for Windows XP, Windows Vista, Windows 7 x86, Windows 7 x64, Windows 8/8.1 x86, Windows 10 x86. If you want to install this driver on Windows 8/8.1 x64 or Windows 10 x64, you need to disable digital signature function first then install this driver.You could refer the below link to disable digital signature function on Windows.http://www.thewindowsclub.com/disable-driver-signature-enforcement-windows Notice :1. Unplug scanner’s USB cable from PC then uninstall scanner driver.2. Hold down the “Shift” key then choosing the “Restart” option in Windows.3. Your computer will restart with Advanced Options. 4. From the list of options displayed, select the “Troubleshoot” tile.5. Next, select “Advanced options” and hit the “Startup Settings” tile.6. Next, select the “Restart” button to restart your PC on the Startup Settings screen.7. You will see the following screen on restart. 8. Press the 7 keyboard key to activate the “Disable driver signature enforcement” option.9. After enter the Windows 10 then you can install scanner driver.10. Connect your scanner to your PC then check scanner device status is recognized or not in Device Manager. Hope this info could help you. Thank you.