Custom HTML + JS not working

Hi! So I made a currency convertor for my page, only problem is the HTML seems to not be working. I added the js script just fine as a hook, and when i add the custom html, in the preview everything seems fine, but when i publish it doesn’t even appear/the script code shows up as text at the end of the page.
So I tried writing a simple <h1> test page </h1> just to see if the text would show up but it doesn’t go through.
i tried clearing the cache several times but it doesnt seem to be working. am i missing a specific tag for wordpress? (this is the first time im working on wordpress.)
thanks !