Annual return for gstr4

A gst registered composite scheme dealer annual return gstr4 filed in f.y.2019-2020.but dealer mistake sales of taxable turnover amount(outward supplies detailes) 1%tax rate goods not reported(entered) table (6) in gstr4 annual return in 19-20.

Question:

1.dealer mistake sales turnover how to adjustment producure in gstr4 19-20

2.composite dealer gstr4 and gst9a both returns filed compulsory in 19-20.

3.inward supplies detailes (b2b) invoices uploaded compulsory

4.dealer mistake sales of taxable turnover amount adjustment in gstr4 annual return year 2020-2021 or mistake sales of taxable turnover amount shown in gstr9a in 19-20 is correct.

5.gstr 4 extension any date and non filing of annual return which penality applicable per day.