Python I have 2 problems with snake game in python

Code
#libraries

import pygame

import random



pygame.init()



white = (255,255,255)

black = (0,0,0)

red = (255,0,0)

green = (0,155,0)



display_width = 800

display_height = 600



gameDisplay = pygame.display.set_mode((display_width,display_height))

pygame.display.set_caption("Snake(alpha edition)")





block_size = 10

FPS = 30

clock = pygame.time.Clock()



font = pygame.font.SysFont(None, 25)



def snake(block_size, snakelist):

    for xny in snakelist:

        pygame.draw.rect(gameDisplay, green, [xny[0], xny[1], block_size, block_size])

    











def gameover_msg(msg,color):

    screen_text = font.render(msg, True, color)

    gameDisplay.blit(screen_text, [display_width/2, display_height/2])





def gameLoop():

    gameExit = False

    gameOver = False

    pos_x = display_width/2

    pos_y = display_height/2

    pos_x_change = 0

    pos_y_change = 0

    randAppleX = round(random.randrange(0, display_width-block_size)/10.0)*10.0

    randAppleY = round(random.randrange(0, display_height-block_size)/10.0)*10.0

    snakelist = []

    snakelength = 1



    while not gameExit:

        

        while gameOver == True:

            gameDisplay.fill(white)

            gameover_msg("Game over, press R to play again or Q to quit", red)

            pygame.display.update()



            for event in pygame.event.get():

                if event.type == pygame.KEYDOWN:

                    if event.key == pygame.K_q:

                        gameExit = True

                        gameOver = False

                    if event.key == pygame.K_r:

                        gameLoop()

                    

            



        

        for event in pygame.event.get():

            if event.type == pygame.QUIT:

                gameExit = True

            if event.type == pygame.KEYDOWN:

                if event.key == pygame.K_LEFT:

                    pos_x_change = -block_size

                    pos_y_change = 0

                elif event.key == pygame.K_RIGHT:

                    pos_x_change = block_size

                    pos_y_change = 0

                elif event.key == pygame.K_UP:

                    pos_y_change = -block_size

                    pos_x_change = 0

                elif event.key == pygame.K_DOWN:

                    pos_y_change = block_size

                    pos_x_change = 0



            if pos_x >= display_width or pos_x < 0 or pos_y >= display_height or pos_y < 0:

                gameOver = True



            

            if pos_x == randAppleX and pos_y == randAppleY:

                randAppleX = round(random.randrange(0, display_width-block_size)/10.0)*10.0

                randAppleY = round(random.randrange(0, display_height-block_size)/10.0)*10.0

                snakelength += 1

              









        pos_x += pos_x_change

        pos_y += pos_y_change



        gameDisplay.fill(white)

        pygame.draw.rect(gameDisplay, red, [randAppleX, randAppleY, block_size, block_size])



        snakehead = []

        snakehead.append(pos_x)

        snakehead.append(pos_y)

        snakelist.append(snakehead)



        if len(snakelist) > snakelength:

            del snakelist[0]



        if snakehead in snakelist[:-1]:

            if not snakehead == snakelist[0]:

                continue

            gameOver = True



        

        snake(block_size, snakelist)

        

        

        pygame.display.update()



        clock.tick(FPS)





    pygame.quit()

    quit()





gameLoop()