Key Sensitivity

[RonVdC]

How can i adjust the key sensitivity in general i mean all sounds to make the soft part sounds louder
I have i light touch when i play

[mikf]

You don't say which keyboard you have, but on most Yamaha arranger keyboards you can adjust the touch sensitivity. Look up the manual for your specific keyboard. The adjustment is not usually big, but you can of course also adjust the volume to just make it sound louder, or vary the compression.
You should also think about whether your touch is just too light, and work on that. If you can produce reasonable volume with normal touch on an acoustic piano, you should not be having any problem on a PSR.
Mike