Install Windows 7 on macoS High Sierra (MBP Late 2011)
If you are happy with Windows 10 and want sound then you will have to install to BIOS boot. The instructions for doing so can be found at Installing Windows 10 without DVD or Third Party Tools. I would recommend first uninstalling the UEFI booting Windows 10 you have already installed. This is not covered in the link given in this answer. 

Another possibility would be to convert your existing Windows 10 installation from UEFI to BIOS booting. I have never tried this to fix a driver problem, but this might be worth attempting. The steps would be as follows.


From Windows, download gdisk.
Copy gdisk64.exe to the Windows 10 flash drive.
Boot from the Windows 10 flash drive.
Open a Command Prompt window.
Use Windows commands to remove the Windows UEFI boot files from EFI partition.
Use gdisk to convert internal drive to hybrid partitioning.
Use Windows commands to install the BIOS boot data and files.
Boot back to Windows.
Maybe reinstall the Window Support Software.