Hello, this is the first time I've had this issue, do note all I did before this started happening was to do a clean install of my operating system, don't know if that has an impact or something.
Anyway, so the default interface and subtitle is set to portuguese brazilian language, I change both to English and go back to the main menu twice to check for add-ons... twice everytime. All is good for that play session. Once I exit the game and relaunch it later it resets back to portuguese brazilian, and there I go again to both settings and rechecking add-ons twice.
Not that the "Checking for add-ons" is the issue here, but since my internet connection is slow and I have to recheck it multiple times everytime I launch my game because language settings reset is becoming an hassle.
What I've tried so far was going in the Documents folder, AC Valhalla ini file and changing the language there and even after making the file read-only IT STILL resets back to portuguese brazilian.. Don't know if this matters but my windows 10 language is set on portuguese Portugal but that shouldn't affect the game language everytime even after I changed the settings in-game.
Last thing, on the Ubifsoft Launcher, on the AC Valhalla settings the language there is set to English too, but the game still launches it on portuguese brazilian.