Hey Brungeshwar,

You have to do it again. You can change everything in your JEE Main 2019 application form, except changing the mode of the exam from online to offline. Sometimes, the server of JEE Main may not be able to take the load or may show error, so you have to try again after some time. Another important aspect is that if you have made some change and submitted the form after changes, then you will not be able to make any further changes, as application correction is just a one time facility. In such a case, you must send a mail to jeemain@nic.in mentioning your problem.

You can definitely change your category during application correction. You also need to pay the additional fee after changing from one category to another, if applicable.