Hello Aspirant,

No changes can be made after the final submit of any SSC application form. It is clearly mentioned in their set of instructions and this is why there is a preview option before the final submission . In that preview you are expected to check all details and modify it if needed . Even when you click the final submit option , they will ask for a confirmation . But do not worry much, the only option left is to either explain the mistake and correct it during document verification , note that this is only for minor mistskes like spelling or wrong 12th or graduation roll number etc , or to send them an email with the concerned mistake and the right information you need to enter along with the proof. You may see whether there is any helpline number and contact them for better assistance. If it is a minor mistake , do not worry during verification the officials may get convinced if you show valid proof .

https://www.google.com/url?sa=t&source=web&rct=j&url=https://competition.careers360.com/articles/ssc-chsl-exam-dates/amp&ved=2ahUKEwj3s8KGlqHuAhUhmuYKHcdaBkkQFjADegQIFhAB&usg=AOvVaw0VdliGwVlM_Yc1Az6A5Coz&ampcf=1

All the best