How can I change the setting in app optimization on my S6 Edge?

A

AC Question

app optimisation s6 edge

Hi, I've never posted on one of these forums before but I always read them for help. I've just got my new S6 Edge (UK) and a few things do seem impractical about it, the main being this app optimisation. This app optimisation stopped my whatsapp notifications if I don't go on whatsapp for a prolonged period (3-4 hours) and I have to go on the app to see if I have received any notifications. I am usually Okay with phone settings as I always read and sort the problem out myself. I went on to settings, battery, detail, and disabled app optimisation for whatsapp, it still continued. So, then I switched off app optimisation altogether for everything on settings and Samsung smart manager, and I'm still not getting my whatsapp notifications until I dont open the app. please can someone help, is my phone a faulty unit or is this a bug or am I needing some guidance, if I do, it would be much appreciated. thanks