The first time one clicks a file with an extension in Windows 8 - windows 10, it will prompt for user choice like this dialog in the screenshot to ask which program one wants to use to open this type of file. if one does not make a choice, it will keep asking one to make a choice the next time of user clicking. if one wants to change the program for this file type, one can right click and then choose the menu "open with" and then select another program, or one can change the default program for the kind of file association in the control panel. With any of the 2 methods one will be able to get the same dialog prompting for user choice. The question is, how can one make windows behave as if one had not made a choice before? I have done the research the whole night, the story is not stored in the registry, I have compared every registry entry of my 2 PCs, they are both the same for the association of file extension. Anyone who has figured out where is this setting located, please do tell me. I think it may be in the "programData" of %windir% or %appdata%/roaming.
Next time you open this type of file it will be directly opened by windows using the program, which windows thinks might be able to handle this extension. It will be directly opened and windows does not again prompt for user choice. How to let windows ask the same user for user choice again, make windows behave as if this user had not made a choice before?. Actually the user has selected a program last time.
Well you can remove the assiocation and leave the registry blank However its a long process as it depends on the file type you want to remove. You can use a tool called FileTypesMan from nirsoft So you can completely remove the association which will give them a prompt. There is also a program called unassoc, do a websearch for it this might be getting interms of what you are doing a simplier UI With the registry this path is located at Code: HKEY_CLASSES_ROOT HKEY_CLASSES_ROOT\SystemFileAssociations\ HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts and then you search for the .filetype but its best to use the tools to avoid deleting anything that you don't wanna
I have already tried your instruction last night, but the behavior can not be gotten back. I compared every registry entry in HKCR and HKCU for the .filetype in my 2 PCs, they were both the same. For the PC, on whose win 10 system I have made the selection for opening that file, win will not ask again. But on the other PC, on whose win 10 system I ignored the dialog for user choice, this meant that I decided to choose the program later. The next time I clicked the file win keeps asking for my choice of program. therefore this setting is not stored in the registry. Anyway thanks for your engagement.