Inspect Source Basics, Two Items: Output fail and Accessibility Options

[Lucas65]

Noob!! When I inspect a page source, say wikipedia.org, my first experience, I find the DOM element for title, double click it, and replace it with "My Wikipedia," Then I hit Enter. However, there is no change in the output sample page. If I refresh, my edit disappears from the source code. I have failed both on Chrome and Edge. What am I doing wrong/

Also, I am low vision and I am having an accessibility issue. If I view "page source," no problem, I can CTRL+. But when I am doing "Inspect Source" and looking at HTML5 DOM elements, CTRL+ fails. I have checked through menus and queried Help. I can find no way to increase the font size to read the code. It is so small for me that I have to hand hold a magnifying glass.

Thank you for any assistance!