How to auto switch input method by app

Solution 1:

I have the same problem and solve it by the following approach.

1. choose System Preferences
2. select the Keyboard option
3. Select the Input Sources tab, and then check the box next to Automatically switch to a document’s input source option

Source: https://www.tech-recipes.com/rx/53194/os-x-switch-language-input-sources-automatically/

Solution 2:

You can try going to system prefs/language & text/input sources and checking the box for "allow a different one for each document," but this may not do what you want.

Source: "Automatic Language Input Change" on the Apple Support community