Why my "edit module" section in language setting does not work?

I am trying to select “English (UK)” as prefered language in “Edit Modules” option of writing aids option -

But after selecting English (uK) this way, it again falls back to English (India). If I reopen the module I can see that it has automatically selected English (India) again.

What is wrong?
I am using - Version:
Build ID: 430m0(Build:2) on Ubuntu 14.10.