acer e5-574g

hi guys im new here... i think a i have a problem with my acer e5-574G.. i've installed some games and everytime i open a game it always returns to the home screen.. everytime i turn on fullscreen i goes back to windowed mode.. i have no idea on how to fix this..i tried to search it on google but I can't any possible answers... i restarted it a couple of times and still does the same thing ove and over again.... tried to scan my system using malwarebytes for possible viruses and found nothing wrong.. pls help