service Po related to multiple account assignment

Hii all,

can u tell me about a setting related to service.

Actually i am trying to do a Capital service PO, since i am going to do for multiple account,when i enter my asset number then one window appears called Account assignment category for line item number, there One tab comes " Number/Percentage" , there i want to select the quantity number wise, but its taking percentage wise. so plz let me know how and where i can change the settings for it.