[otrs] changing the new ticket form in customer interface depending on the ticket type

Hello, colleagues, I'd like to change the form used to create a ticket by the customer depending on the ticket type chosen. I noticed that the form refreshes each time the ticket type is changed. can somebody point me in the right direction to search? Later I goona have the similar task for agent (phone ticket, priority update). I tried to google but could find no useful information. Regards, Anton.