Video and sound problem.

Hi.. i have 2 problems.. or maybe one question and one problem :P
1. do i have to change my screen resolution every time i want to play.. to 1080x768?? i have screen resolution 1980x1080

2. i dont have sound in game.. i can only hear footsteps and bullets. no music.. no radio msg... i checked the option and everything is at maximum. i have 5.1.. (ofc they work).

i hope to have some answers soon.
thnx soldiers..