How can I edit a .json file to modify my contact form fields?

[IMASJEWELRY]

Hello!

Someone please help! 

Im trying to fix my contact page, that stupid .json code is crazy! This is what it looks like:

{
"sections": {
"main": {
"type": "main-page",
"settings": {
"padding_top": 36,
"padding_bottom": 36
}
},
"form": {
"type": "contact-form",
"settings": {
"heading": "",
"heading_size": "h1",
"color_scheme": "scheme-1",
"padding_top": 36,
"padding_bottom": 36
}
}
},
"order": [
"main",
"form"
]
}

I removed the "phone number" text, and changed it to 'subject' but now when i want to type something in the 'subject' field i can only enter Numbers, NOT letters. How can I fix that? I Dont want a phone number field, i want a Subject field instead. Just Name, Email, Subject and Message field. Someone please help! I noticed that the code I get on my "page.contact.json"  page is Not the same type of code I saw on other posts?? Why is the code different if it's the same website template. This is the link of my form. 

https://imas-jewelry.myshopify.com/pages/contact

I also want to make the subject and Message fields a requirement (*) 

Someone Please HELP!