Plz guide in filing gstr 3b

Sir Please help me in filing my GSTR 3b....

I am Filing my GSTR 3b for the month of August 2018. The available ITC at the end of July month is CGST = 13,600/- & SGST = 13,600/-

NOW, OUTPUT TAX for Current month is CGST = 5446/- & SGST = 5446/-

            INPUT CREDIT of Current month is CGST = 13,798/- & SGST = 13,798/-.

BUT, While Proceeding for Payment Window, in Credit LEdger Balance it is showing as CGST = 14,209/- & SGST = 14,209/-

Where as the Credit Available should be CGST = 21,952/- & SGST = 21,952/-

Please Guide me What should I do now ? Balance ITC is Autopopulating. Can I Alter this? or I made any mistake in Return. Am Filing Returns for the first time, plz guide me sir.