sister thank you for your response. but, I had a doubt,
In application i selected vit ap. I written viteee exam well.and I recently got the information that VELLORE  Campus is best.now, I decided to study in VELLORE. so, is there any chance to study in VELLORE. and to change my preference before counselling.

During counselling if you're rank is good enough you might manave to get a seat at VIT Vellore it all depends on the availability of seats and your rank now. I hope you understand.
If you still have doubts you can call their helpline number.

Debosmitha Bhattacharyya Sister I scored AIR 8K in the entrance exam. But during counselling I gave my priority first to AP due to the force of my mom. Now I didn't get selected in any other top college.
After the counselling results I got VIT-AP
Can I change my seat from Ap to Chennai
I can afford atmost 4lakhs.