How do I change the Music, SFX, and Blood options?

You can turn these features on or off by tapping the circled icon on the right of the respective option. If a green tick is shown, it means that the feature is on. 

Turning Music off will mean that no music will play throughout the game. 

Turning SFX off will mean that no sound effects will play throughout the game. 

Turning Blood off will mean that you will not see any blood when you shoot enemies in the game.