I've been trying to figure this out for a couple hours now and can't seem to find an answer that will work or is for the version I'm using so here it is:

I am using SharePoint 2016 online I believe is what it would be. I have SharePoint designer 2013 to customize my page.

I have my AllItems.aspx\* open and I am trying to customize the button that says "New Item" on a custom list to say "New person" instead. I know I have to do it with javascript (or that's the way it seems) but I cannot figure out where to put it and what exactly the javascript would be. Any help would be great. Thanks.