Python: My if statement is not working but I don't get any error?

I am creating a tic-tac-toe game and the move_base function in my script is not working. I have seen this type of if statement used before and I don't know why the function is not working. There are no errors but the function doesn't update num_word or moves. I do not have a lot of python experience so I do not know what I am doing wrong. I will add more features to the game but I can't because the basic part of it is not working. I have not seen any other place that tells me how to fix this.

#tic tac toe game
#global variables
game_over = False

#game script
def game():
    #game variables

    #positions on the board
    one = '1'
    two = '2'
    three = '3'
    four = '4'
    five = '5'
    six = '6'
    seven = '7'
    eight = '8'
    nine = '9'
    positions = [one, two, three, four, five, six, seven, eight, nine]

    num_chosen = ''
    #moves in the game
    moves = 0

    #prints board
    def board():
        print(f'{one}|{two}|{three}')
        print(f'{four}|{five}|{six}')
        print(f'{seven}|{eight}|{nine}')

    #how to check who won
    def check_win_base(xo, num1, num2, num3):
        if num1 == xo and num2 == xo and num3 == xo:
            if(xo == 'x'):
                print('x player wins')
                game_over = True
            elif(xo == 'o'):
                print('o player wins')
                game_over = True
    #check_win_base applied to all numbers
    def check_win(xo):
        check_win_base(xo, one, two, three)
        check_win_base(xo, four, five, six)
        check_win_base(xo, seven, eight, nine)
        check_win_base(xo, one, four, seven)
        check_win_base(xo, two, five, eight)
        check_win_base(xo, three, six, nine)
        check_win_base(xo, one, five, nine)
        check_win_base(xo, three, five, seven)

    #checks if game is a draw
    def check_draw():
        if moves == 9:
            print('The game is a draw')
            game_over = True

    #how to pick a square
    def move_base(xo, num_word, num):    
        if num_chosen == num:
            num_word = xo
            moves += 1
    #move_base applied to all numbers
    def move(xo):
        move_base(xo, one, 1)
        move_base(xo, two, 2)
        move_base(xo, three, 3)
        move_base(xo, four, 4)
        move_base(xo, five, 5)
        move_base(xo, six, 6)
        move_base(xo, seven, 7)
        move_base(xo, eight, 8)
        move_base(xo, nine, 9)

    #all the required functions put together
    def turn(xo):
        board()
        print(f'{xo} move')
        num_chosen = int(input())
        move(xo)
        check_win(xo)
        check_draw()

    turn('x')
    turn('o')
    turn('x')
    turn('o')
    turn('x')
    turn('o')
    turn('x')
    turn('o')
    turn('x')

#checks if game is over or not
if game_over == False:
    game()
else:
    print('Game Over')