To set notifications, tap the gear icon at the top left hand side of the game screen, then tap Setup Notification Settings.
This will open a menu listing the different types of notifications that Food Street sends.
Go through the list and set your permissions for each type.
The green check mark indicates that the setting is on, tap the other side of the button to turn the permission off.
Once you have set your preferred notifications settings, please wait a few minutes (or visit Stella's restaurant) before closing the game as this should ensure your settings are saved.