CET subject means ?

Please share details that I can help you better.. 

if you have already submitted the application form. you can get back to edit the subject,

but in case if you haven't yet finally submitted the application form you can click on the final submission option the system will generate two options edit your profile or final submission. click on edit profile and change the subject but

again I may repeat if you have already done the final submission you can't just do the above-prescribed steps.