Yaesu CW audio and DSP settings for low signals

Yaesu Ft-710 CW audio and DSP settings for low signals

 am new to the FT-710 and operate CW . I notice when listening to weak CW signals S2 S3 etc... that there is a high pitch hissing noise as background noise. I tried some settings as CONTOUR on the DSP but the hiss is still there in the background. 

Any suggestions on ways to quiet the hiss ?

Try the various Receiver Audio settings as described on page 46 and 47 in the English Language Manual.

Use the Hi-cut setting in the menu and set to 2600 or maybe 2800 with 18dB/octave slope for SSB. For CW, set to 700Hz with 18dB/octave slope.  Also, for CW, use APF and set DSP width to 150Hz or less. Use DNR at algorithm 10 to 15. You can go to the FTdx10 playlist and watch numerous videos on the subject. 

I have the following settings in CW mode:
DSP
Shift: off or 0Hz
Width: 100hz
Notch: 520 Hz
Contour: Off
APF: ON at 0Hz
DNR: ON level 15 algorithm
AGC: Auto
DNF: Off

CW Settings
AF TREBLE GAIN: -13
AF MIDDLE TONE GAIN: 0
AF BASS GAIN: 0
AGC FAST DELAY: 160 MSEC
AGC MID DELAY: 500 MSEC
AGC SLOW DELAY: 1500 MSEC
LCUT FREQ: 500 HZ
LCUT SLOPE: 18 DB/OCT
HCUT FREQ: 700 HZ
HCUT SLOPE: 18 DB/OCT

Any advice on how to get rid of the hiss / underwater noise effect would be greatly appreciated. Or post your setting here and I can try the out