Did you test to make sure Javascript and Jquery work in your template? Sometimes there is an issue with not enqueuing the scripts properly in WordPress.
Does the string already exist somewhere on the page? You really should be fixing this through WordPress/PHP, but if you can’t for some reason the following will work:
$("document").ready(function(){
$("h1").html("Covered California - Outreach, <br> Education & Enrollment")
})