How to highlight (make yellow) text in notes

I tried the markup over and over and it doesn’t work!

But you actually CANNOT. You can highlight all kinds of things. But you cannot highlight typed text. You can highlight text from other places like a web page, etc., then import the screenshot into notes. But you cannot highlight text that was typed in Notes.

You can highlight text in the Notes App using Markup:

Use Markup on your iPhone, iPad or iPod touch – Apple Support