Why when my s6 is ringing in the beginning the sound is too loud

[AC Question]

When my s6 is ringing in the beginning the sound is too loud and than it becomes normal? It was the other way arround befor the update to Nougat 7.0.
I don't know if it is Android or Samsun fault but as a whole Nougat's design is aweful and difficult to use. marshmellow was much easier and intuiutive and logical. Especially the calendar.