Question Loading and Saving to a text file

I have a csv text file in my assets folder and I want to be able to save data in it and read from it I thought this would be easy but I've been looking for solution for days now.
the closest thing I found was using streaming assets folder and unity web requests but I lost the scripts and I can't write it again for some reason I keep forgetting something
All of this is not an issue in the editor but when I build it for Android it doesn't find the directory