Hi Aditya! 

Greetings! 

Once you got the seat in first round and then you chose float option and go into the second round then you will have to compulsorily secure the 2nd round seat. You don't have the option to go back and take the previous seat. Bcoz that seat got alloted to another student in the next round. 

So, If you have got your favorite seat in the first round then secure it. 

Please upvote if this was helpful to you. Thank you and good luck.