Purchase Return in GSTR 3B

DO GUIDE ME IF PURCHASES ARE LESS IN THE MONTH WHEN GOODS ARE RETURNED RESULTING IN NEGATIVE INPUT.WHERE TO SHOW THIS EFFECT IN GSTR 3B

i had a conversation with the hepldesk they said there will be an option in GSTR 3 to fill the amount of purchase  returns but iam not sure about it , its better you rais a sale invoice insted of debit note

Dear Sir

When i creat debit note (Purchase return) in gst then increase in my sale taxable value in GSTR-3B.

it is the seller only who will issue the credit /debit note. Receiptant is not allowed