For me, it's very dependent on what, where and why I'm reading.

If I'm practicing Spanish, for example, and am focused on understanding, I will read in my head so that I don't get distracted by my pronunciation. It allows me to focus on the meaning and how the sentences work.

But if I want to work on my speaking, I will read aloud so that I can "tune" my ears and mouth to the sounds. I usually don't understand as much though, so I tend to do this less often.

If I'm reading in English, my native language, I will almost always read silently because I can go so much faster. I don't have to wait for my slow mouth to catch up. Unless I'm reading to someone, in which case, reading silently would be rather counterproductive.

It depends on what you are reading, if your password ,is better quiet.

Silent.