how to change alternate quantity in sales bill entryyy

how to change alternate quantity in sales bill entryyy

 

write in qty column
number base unit name=number alternative unit name
like:- if the conversaton is 1 ctn=12pcs but you have to set 1ctn=15pcs in sales bill
then write in qty field 1ctn=15pcs

 

thank you

 

Thanks, I do the same way as you suggest