Dear Wendy Gibbons
Thank you for posting in the Microsoft community.
Regarding your question, there are many programs on the web for modifying the registry that
HKEY_CURRENT_USER\SOFTWARE\MICROSOFT\WINDOWS\currentversion\Explorer\FileExts.bat
There are many items under this program directed to cmd.exe %1
These items need to be modified to the main program you need.
Of course before doing this it is recommended that you back up the entire
HKEY_CURRENT_USER\SOFTWARE\MICROSOFT\WINDOWS\currentversion\Explorer\FileExts.bat
registry entry.
I found that I had the same problem as the user at first in the original post, but then realized that there were several OPEN WITH items that were not modified together.
In all honesty, it's a complicated solution and not recommended.
Disclaimer: Generally, modifying registry subkeys or work group is intended for advanced users, administrators, and IT Professionals. It can help fix some problems, however, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For further protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click How to back up and restore the registry in Windows - Microsoft Support to view the article.
Hope the above information can help you
Best Wish
Shawn Z | Microsoft Community Support Specialist