Hello,
You may check the registry value for " Let me use a different input method for each app window" setting, it is stored in the UserPreferencesMask binary value for the HKEY_CURRENT_USER\Control Panel\Desktop registry key, but this UserPreferencesMask binary value is also used for other settings.
I did not use the default input method, so my registry value is as under:
Reference: How To Set A Different Input Method For Each App Window
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This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added 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, see How to back up and restore the registry in Windows - Microsoft Support.
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