As per the rules, you can not change the priority order that you set during the first round. Only in the last spot round, candidates who have not been allocated any seats can change their preference order.

Well, last year JOSAA had a special seat allocation round for NITs/IIITs/GFTIs to fill in the seats left vacant even after the last round. In that round, candidates were allowed to change their initial priority order and re-fill the choices. But ofcourse, you can not rely on such uncertainities.

Fill your choices carefully. You may not get another chance to modify it.

All the best.

Hey! Hi Amitava Basu.
Sorry to say but You Won't be able to do it now.
You cannot alter the choices now.
You can lock the choices only once throughout the Counselling process.
Hope this helps you.
Thanks.