Date of Birth issue

Hello sir, Its been 5year since I owned a passport.It will get expired by 2022.5Years back I was in class 10th and due to a mistake I registed a wrong DOB in my 10th Icse board i.e 26th feb 1994.The real one is 16june ,1992.Based on it ,we made a birth certificate since the real birth certificate was not been found at that particular time.Also I didnt gave much important to this default.Now after 5Yr ,when my sister too aplied her passport,the problem started.her dob is 28march,1994,whereas my registered one is 26 feb,1994.the problem is one month difference. Now I regret that I made a big mistake by not taking seriously this matter at the time of icse registered.i was also hurry in going for a holiday to Hong kong. Now after lot of complain ,we got the real birth certificate .I need help further,like how to change the previous affidavit n change this Dob.My placement too will start after 5month n i need to sort it out ASAP.I cant even change my 10th mark certificate since it already 5yr n icse dont entertain after a long gap.