How to change Windows file associations for files accessed via MTP (such as Android device files)

Question

When double-clicking to open files in Windows Explorer on a device connected via MTP, how does one change the target application?

The OS is Windows 7, and the MTP device is running Android.

I've changed the file associations via Windows' Default Programs UI, as well as by using NirSoft's excellent FileTypesMan tool. For local files, the file associations work exactly as expected. Via MTP, however, changing file associations seems to have no effect.

In particular, I am trying to change the associated program for viewing JPG (JPEG) image files stored on the Android device. Currently, via MTP, they load in Windows Photo Viewer, and I want to use a third-party tool instead.

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UPDATE

I've been actively working to figure this out, and here are some things I'm trying or thinking about trying. Any help is appreciated. Obviously, I'm making backups and not changing anything I can't revert.

• I've been experimenting with modifying the SystemFileAssociations areas of the Windows registry. No success yet, but it looks like a possibility.
• I've been looking at registry keys that begin with WPD. WPD stands for Windows Portable Device, which appears to be relevant.
• I'm looking at UserChoice registry keys. Windows doesn't like people changing those keys, but I think it's likely much easier in Windows 7 than in Windows 8.1 or Windows 10 (in Windows 10, there is a corresponding hash, that if it doesn't match, the value gets reset by the OS).
• I experimented with assoc and ftype from within an elevated command shell. No success yet with that.

One thing I've noticed is that when an MTP device is opened in Windows Explorer, it's not the Open verb that is actually used when the user double-clicks. It's the 'Preview' verb. I can successfully modify the Open verb's actions, but so far I haven't been able to make it the default verb, nor have I been able to change the action taken by Preview.

Answer 1

THIS IS A SPECULATION OF WHATS HAPPENING, TAKE IT WITH A GRAIN OF SALT

I SUSPECT two reasons why the Win7 is not respecting filetypes/extension preferences:

1. According to Wikipedia I believe Microsoft MADE MTP & implements it with the WMP (Windows Media Player) framework so its entirely possible Microsoft simply ignores your preferences & uses its built-in media player (WMP) & picture viewer...they've done it before
2. MTP isn't a filesystem & may not allow the OS to be AWARE of filetypes/extensions of the connected devices files so can't respect your application preferences related to those filetypes/extensions

My Win10 (v1607 Enterprise LTSB 64-bit) & Samsung MTP phone DO NOT HAVE the issue so it must be unique to Win7? If I get time I'll try to test it with a Win7 PC.

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EDIT

Win7 Pro SP1 x64 laptop here DID respect when I changed .MP3 file association from Windows Media Player to Internet Explorer. Opening file on local drive & MTP device popped up IE with a download/open prompt. So it seems the problem may be unique to you or maybe bad Win update? Laptop here hasn't checked for updates since 3/7/15. I'll try to post pics later

Possibly helpful links:

• https://docs.microsoft.com/en-us/windows/win32/wmp/mtp-device-extensions-for-metadata-transfer
• https://docs.microsoft.com/en-us/windows/win32/wpd_sdk/supporting-mtp-extensions
• https://answers.microsoft.com/en-us/windows/forum/all/how-do-i-open-documents-and-other-files-from-mtp/e09950e1-bd1a-446d-a72f-27fdce86cddc
• https://digital-forensics.sans.org/summit-archives/dfir14/USB_Devices_and_Media_Transfer_Protocol_Nicole_Ibrahim.pdf

Answer 2

Have you tried using FTYPE to change the association?

Ftype jpegfile=C:\Complete\Path\Of\3rdParty\Tool.exe %1

Microsoft's FTYPE command or here Windows "Open" function not working for .LIS files

I suspect @gregg 's answer is the likely issue though