Gooner44 is right. You are setting your high score when the game begins. For your graph above, you should only load (get)the value if the save gave is valid. If there is no saved game, set the HighScoreNumber to zero (which I’m assuming your HighScore variable is by default) and save. At the END of play, you should compare your current level score to HighScoreNumber. if you level score is higher, then save that value into HighScoreNumber and save. If not, the leave HighScoreNumber as-is and you are golden.
So, the first time playing your level, assuming you score something, your level score will be higher than your saved score and you can update then and resave.
Make sense?