what pitch for 737

Hi What is the correct pitch i should be flying at on level cruise altitude. Reading what i found on a 737 technical web site it says 4 deg. All of my 737's seem to fly at 6/7 deg. From outside looking at the aircraft the nose always seem to be to high as it is tail heavy. I cant find anyway to adjust pitch for a more level looking flight. This happens whether i have a full fuel tank or running on fumes. Thanks Shaun