So I learn this Windows 10 in-place upgrade method to keep the existing app. and files from “Reinstall Windows 10 Without Deleting Your Software, Files or Settings: Perform an ‘in-place upgrade’ to fix a buggy Windows installation, By Mark Turner on December 26, 2018. Detail: https://www.techspot.com/guides/1764-windows-repair-keep-all-your-files-intact/
Actually starting the in-place upgrade
Start the Windows setup (setup.exe) by mounting the ISO or opening the Windows USB installation drive from the File Explorer.
Windows 10 has native support for mounting ISOs by right-clicking and choosing Mount or by using the following PowerShell command (our installation was so broken that the right-click option wasn’t available to us):
Mount-DiskImage -ImagePath "C:\FileName.ISO"
After launching setup.exe or the Media Creation tool, you’ll have the choice to upgrade now or to create an installation ISO/USB drive — you want to Upgrade this PC now. You might be prompted to download updates prior to this option being available
The installer will perform some initial setup/scans and eventually ask what you want to keep on the new copy of Windows.
If you intend to keep your currently installed software on the repaired operating system, make sure that “apps” are listed and not only “files” (Keep personal files and apps).