I own a Vodafone Smart 2 (rooted, Stock ROM). I usually have the Internet turned off and I only turn it on (WiFi) on the night at home. When I turn on the Internet, my phone starts receiving lots of notifications from Facebook Messenger. It receives one notification per message, even if I've already read it before on another device. The phone keeps ringing for like 30 seconds and then it stops. If there are unread conversations, the notification stays on the bar; otherwise if I have read it before, it rings but then disappears from the bar.
Any idea on how to stop notifications of messages that I've read before? Any suggestion is welcome! Thank you.