This is not a question but an observation. I have VS05-2019 installed and VF10 and VF19U5 on 8.1.The VF10 works with VS05 and the VF19U5 works with VS13-VS19. I can select in File Explorer an association for f90 directly to VS05, VS13,VS15 only, but when I select "Microsoft Visual Studio Version Selector" the files open in VS19.
Would such be because of the supplied shell thing that I can't directly chose the devenv.exe for VS17 and VS19?
You might be able to do this with a shortcut that runs a .bat file that changes the environment prior to launching Devenv.
Note, you can drag and drop a file onto the shortcut (if shortcut accepts drop).
The "Version Selector" seems to always pick the latest VS version, I rarely have the desire to open .f90 files from Explorer - what is your use case for this? This shouldn't stop you from using .f90 sources in whichever version of VS you choose.
My use case is settling on/in one environment so I can focus quickly on the code, not "homemaking". I usually open a "f90" file from explorer; a solution I open from a dedicated directory for that version.
I'm fine with the results of using "Microsoft Visual Studio Version Selector" as it opens in VS2019. When opening solutions, I have learned to avoid it since it seems to always select the wrong version, usually after a service pack or update of one of the compilers. VS2019 at first was nutty so I used 17 or 15, but when 19 worked better on remote Linux dev than 17 a few months ago, it seemed maybe time to move to 19.
Locate the MS VS of your interest. On my system
Start | All Programs | Microsoft Visual Studio 2010
Then Right-Click on the Microsoft Visual Studio 2010 program (not the folder of same name).
Find convenient spot on desktop, Right-Click, and choose Paste ShortCut
Now for a test, open Windows Explorer. Select one, or if you wish, multiple, .F90 files and then drag and drop them onto the new shortcut.