Is there a way to change the button sound effect on ANY song while i play ?
And also i have 2 songs where it gives me some kind of a error when i start them about the button sound effect, and then after the error i can play the songs but without any buttos SE, but still i want to change the button SE on any song is this possible ?

Two ways to do that.

1) Change sound located in KHC/PPD/songs/*scorename*/sound (it usually have the name sound.wav). So just pick the new sound you want, put it in this folder, delete or rename old ound and rename new sound to sound.wav (or to other name pointed in soundset.txt in score folder).
You can download archive with different sounds here:
http://seesaawiki.jp/ppdxxx/d/%a5%dc%a5%bf%a5%f3%b2%bb%ca%d1%b9%b9

2) Simply use any of available SEChange mods.
This one, for example script/edefaf1743a3144ea0010f1965701ab6
You can change sound in options right in the game.

thank you for the help <3