How to call back specific file info for different players using c#?

I know how to SAVE each player's individual registration info; player name and password. HOW do I call it back for different scripts such as saving their gold or experience?

I am using this file in the player's system: C:\Users\kathe\Desktop\UnityTestFolder\" + Username + ".txt"

Do I have to use the "form = (Username + Environment.NewLine + Email + Environment.NewLine + Password);" everytime on everyscript and add the "gold amount" to the end?

I am so very lost! I don't know how to call back the different player's individual information on my different scripts for saving/displaying gold & for saving/displaying experience.

AND PLEASE I do NOT want to use any prefab buttons or instantiate of buttons.