NTA has released an official notification regarding All India Quota. Irrespective of your choice in that field, you will be eligible for all States for All India Quota except for Jammu and Kashmir and Ladakh because Jammu and Kashmir and Ladakh do not participate in All India Counselling. You cannot make changes to this field because it doesn't  matter what you enter in that field. This is because, NTA has issued a clarification that you can fill any State details against All India 15% State Eligibility field. You can mention any State except for Jammu and Kashmir and Ladakh as they do not participate in All India Counselling. Irrespective of the State you mention there, you will be eligible for 15% All India Counselling of all States except for Jammu and Kashmir and Ladakh.