Sometimes the game "forgets" your choice. You can force it through config files:
Getting the Far Cry 4 English language pack to work correctly can be tricky, especially if you have a version locked to another language—most commonly the Russian release. This guide details how to install, fix, and troubleshoot English language settings for the PC version. 1. Official Methods to Change Language far cry 4 english language pack work
fcc_main_english.dat and fcc_main_english.fat in \Far Cry 4\data_win32\worlds\fcc_main . Sometimes the game "forgets" your choice