sure but how xD i need a tutorial plz ..
Well, I think the easiest way is to pop it into Rig Manager, select the Rig so the Info window on the right-hand side reveals all the information fields, and in the top pane, called "Rig", click the 3rd field from the top, labelled "Instrument", and select "Bass" - there are only two options, "Guitar" or "Bass", and hit RETURN... done!
So easy, even I could do it, which I did, but I can't change your copies. Thank you for not laughing at my suggestion, Brother B.
OK, you can laugh now.