Hi Nidhi,

If you are allotted a seat in say 2nd or 3rd of counseling then if you choose to accept it you would be asked if you want to select the YES UPGRADATION which would enable you to change your accepted seat at a college provided you are allotted a different seat in the successive or mop up round where you can change your previously accepted seat and select the new seat allotted to you or keep the seat which you was previously allotted to you.

BEST WISHES!