Hello 
sorry
it is from this method
Switch scenes in monogame? to create the menu
I tested it works great 
now i put my code in order
the high score works
in the event of a collision it returns me to the menu with the best score
on the other hand if I turn off the app
it no longer displays the old score
i have to find the way how to display the old score
do I have to load the score for example in my playGame method?
can you help me thanks in advance