help changing footer on home page
It seems like you're not a web developer? This is a very broad question unfortunately which will make helping hard. It depends almost entirely on how the previous agency decided to build your website, as "a footer" is not built-in functionality, but instead part of the design.

Typically, a footer would be controlled from a _layout.twig file in the templates directory. The content inside it may be "hard coded" or dynamically controlled from the CMS - there's no way for me to know. You'd need to look at the content of that file and see if you can find any text matching the text you see in your footer. Be aware though, that a footer template is usually site wide and not specific to individual pages; a change in _layout.twig would most often mean a change everywhere on your website.

You may be best off getting in touch with the prior agency, or perhaps a freelancer, and asking them to take a look.