在我目前的代码中，我可以注册一个由电子邮件和密码组成的新帐户，登录并重置帐户密码。但我的代码有一个大问题：每当我想更改某个帐户的密码时，它会重写整个文件，删除现有的任何其他帐户，并将其替换为登录帐户的电子邮件和更改的密码。

# import all necessary packages to be used
import csv
from IPython.display import clear_output
# handle user registration and writing to csv
def registerUser( ):
   with open("users.csv", mode="a", newline="") as f:
           writer = csv.writer(f, delimiter=",")
           print("To register, please enter your info:")
           email = input("E-mail: ")
           password = input("Password: ")
           password2 = input("Re-type password: ")
           clear_output( )
           if password == password2:
                   writer.writerow( [email, password] )
                   print("You are now registered!")
           else:
                   print("Something went wrong. Try again.")

def change_password( ):
    with open("users.csv", mode="w", newline="") as f:
        writer = csv.writer(f, delimiter=",")
        email = input("Please type in your E-Mail: ")
        newpassword = input("Type your new password: ")
        newpassword2 = input("Re-type yor new password: ")
        clear_output( )
        if newpassword == newpassword2:
            writer.writerow( [email, newpassword] )
            print("You succesfully changed your password!")
        else:
            print("The password's don't match.")

# ask for user info and return true to login or false if incorrect info
def loginUser( ):
   print("To login, please enter your info:")
   email = input("E-mail: ")
   password = input("Password: ")
   clear_output( )
   with open("users.csv", mode="r") as f:
           reader = csv.reader(f, delimiter=",")
           for row in reader:
                   if row == [email, password]:
                           print("You are now logged in!")
                           return True
   print("Something went wrong, try again.")
   return False
# variables for main loop
active = True
logged_in = False
 # main loop
while active:
   if logged_in:
           print("1. Logout\n2. Quit\n3. Change password")
   else:
           print("1. Login\n2. Register\n3. Quit")
   choice = input("What would you like to do? ").lower( )
   clear_output( )
   if choice == "register" and logged_in == False:
           registerUser( )
   elif choice == "login" and logged_in == False:
           logged_in = loginUser( )
   elif choice == "change password" and logged_in == True:
       change_password( )
   elif choice == "quit":
           active = False
           print("Thanks for using our software!")
   elif choice == "logout" and logged_in == True:
           logged_in = False
           print("You are now logged out.")
   else:
           print("Sorry, please try again!")

我正在寻找一个解决方案，只取代已经登录的帐户的密码，不要求帐户的邮件，因为更改密码是唯一可能在我的代码时，用户已经登录。