adding information to a dictionary.

[Justice_py]

So I'm creating a basic program where when it is run it asks the user if they have an account. If they enter "n" (no) then they are prompted to create a username and password. If they enter "y" they can login. the issue is that the username and password is only stored as key:value while the program is running, and is forgotten as soon as it is exited. If I manually enter into the dictionary a key:value then it is saved as an account and I can login to it. I'm trying to make it so that the account created when the user signs up is automatically put into the dictionary. Here is what I have:

users = {"John":"Doe", "GEO":"Rock"}
status = ""

def mainDisplay():
    status = input("Do you have an account?: y/n? Press ! to quit: ")
    if status == "y":
        existUser()
    elif status == "n":
        newUser()
    elif status == "!":
        quit()

def newUser():
    createAccount = input("Please create a username: ")

    if createAccount in users:
        print("\nUsername already taken.\n")
    else:
        createPass = input("Create a password")
        users[createAccount] = createPass
        print("\nUser created\n")

def existUser():
    login = input("Enter your username: ")
    passw = input("Enter your password: ")

    if login in users and users[login] == passw:
        print("\nLogin successful.\n")
    else:
        print("\nError: invalid username or password and/or invalid combination.")

while status != "!":
    mainDisplay()

Thanks


*John:Doe and GEO:Rock are key value's that I put in just to test its ability to save an account.