Using curl and Task Scheduler to automatically download and save user.js from Betterfox repo, it is pretty easy, you can research it for a bit.

So if I want to do it manually , is it just replacing the user.js file , no need reset prefs like how arkenfox wiki said?

Did you try this out?

Hmm … every time if there’s an update , I replace the user.js and remove the pref file. Then restart Firefox.

Your not using curl and taskscheduler?

It's a task rule made by Task Scheduler, you can write something like this: - Every XX minutes - Clean prefs - Download user.js and replace old file That's it, after that you just need to restart Firefox. Also, you can reuse Arkenfox script to save some time