Per app input language Windows 10
Solution 1:
In my "Windows 10 Pro" "Version 1809" is not this settings in "Control Panel" anymore.
It is possible to set it in this way: "Start menu" -> Settings -> Find "Typing settings" -> Advanced keyboard settings -> check checkbox "Let me use a different input method for each app window"
External link: https://www.tenforums.com/tutorials/102999-turn-off-use-different-keyboard-layout-each-app-window.html
Solution 2:
Please try this option, and then set your preference input method for different apps:
Start > Settings > Time & Language > Region & language > Additional date, time & regional settings > (under Language) Change input methods > Advanced settings > (under switching input methods) Check on "Let me set a different input method for each app window"
Solution 3:
As of 03.12.2020, using Windows 10 Pro, the option goes in:
Settings -> Devices -> Typing -> Advanced Keyboard Settings
(facepalm)