Modern browsers are pretty similar, so switching from Chrome to Firefox was no big issue…

… except that when I searched something on a page with STRG + F / Ctrl + F, only the first match was highlighted.

This was a major annoyance.

Was?

Yep. Turns out there are two ways to enable highlighting for all matches.

Via Keyboard Shortcut

In search mode you just need to hit Alt + A.

Hit it again to deactivate it.

Via Configuration Settings

In the URL bar type…

about:config

hit enter, and then set

findbar.highlightAll

to true.

P.S.: The keyboard shortcut also toggles the configuration settings.