Problem with audio out [D6100]

[Quattro1]

Hello
Wanted to ask you about audio.

I have connected to tv SAMSUNG UE D6100 music centre. Music centre have RCA input. But I can't connect them anywhere on my tv. So my solutsion was SCART what has RCA input.
So at this moment, my tv has SCART RCA output what is connected with RCA with music centre and that plays audio with crazy speakers and subwoofers.

When I wathc something on cable tv, audio is working in tv speakers and in music centre speakers.
But I have 2 problems with this solution:
1) This solution with cable-tv has 1 problem: audio is out of sync. There is under audio (tv menu) somekind of tool, what can adjust the audio delay. I have tryed this, but still, audio is the some or it goes more out of sync when adjust this delay stuff under tv menu.
What is solution about this?
At the moment my only solutsion about this is to turn tv sound off and let the music centre speakers play alone. But together, they are way out of sync.

2) music centre audio works only with cable tv. When i want to watch something on recorded flash drive(2,5") or some random movie on flash stick, then there is NO audio in music centre speakers.
What is about that? Why they not working?
What is solution about this?

Or I do something wrong in tv menu or something wrong with cables?? But still, this very powerful music centre has only RCA audio input (L and R connector(red and white)- you know, the usual audio input/output cable).

I saw, that the TV has optical audio output? Or can I do something, to get audio working in my music centre with only RCA cable? Or I should change TV output holes (to what)? Or scart output is wrong?

Please help. Would like to get this audio working perfectly. What should I do?