some apps are not listed in the list of apps that can appear on top, notifications pop uo while using other apps, any solution for that???

hi guyskindly help me to fix this issue, my whatsapp is not showing in the list of apps that appear on top list, it's annoying to have notifications while using other apps, kindly help me out to disable these notifications.thanks in advance

j5pro 2017 supports usb otg or not??