Hi Aryan Gupta.

You have to choose Freeze/Float/Slide option after an allotment.

Freeze means you are going with the allotted seat and don't want the seat to be upgraded in subsequent allotments.

Float means you're accepting the seat, but would like to be upgraded to higher optiopns in susequents allotments.

Slide means you're accepting the seat, but would like to be upgraded to a higher option in the same institution.

So, If you do not choose freeze, you have to choose Float, if you would like to get a higher option and Slide if you would like to get upgraded to a higher option in the same institution where you got the seat in round 1 allotment.