Press "CTRL+J" on sale window=> Switch Over window will appear => Select Data Entry => Marg Erp 9+ Accounting window will be appear => Select Sale Return => Sale Return window will be appear =>  Sale Return window will be appear in which user have to select the "B" option of challan i.e. for Retail => Bill Retail window will be appear => Click on Modify =>Modify window will be appear select options as per the user requirement => sale return challan window will be appear select bill which user wants to modify => Click on modify => Make changes => Press "Ctrl+w" for save.

NOTE :-"CTRL+J" Option can be use anywhere in the software.