Some notifications can't be turned off unless you have categories enabled, as if there is one category that's required, the slider will be disabled for the app. To turn on categories go to settings/notifications/advanced settings/manage notification categories in each app. Then go to the app where you want to turn off notifications, select notifications, select categories and turn the sliders off for each category. Bear in mind that some notifications just cant be turned off, but you can make them silent, either by selecting silent for that category (some don't let you) or choosing "silent" as the notification sound for that category. Which apps are sending you incessant notifications?
