Whatich historical sites have you visited? Which historical sites have you visited?

Here "which" is the best word choice

I have visited the Anne Frank's hiding place in the Netherlands when I was 20 years old with my cousin's family. I visited the Anne Frank's hiding place in the Netherlands when I was 20 years old with my cousin's family.

"have" sounds a little unnatural here

I was impressed, but more than that, I felt sadness quietly. I was impressed, but more than that, I felt sadness quietly.

"I impressed" means you impressed someone, but "I was impressed" means YOU were the one who was shocked. So, was impressed is correct. Comma after that

I was impressed, but more than that I felt sadness quietly. I was impressed, but more than that I felt sadness quietly.

Since "impressed" is a state of being it requires "was" (because this sentence is in past tense).

I was quite impressed, but more than that I felt sadness quietly.I felt sad on the inside I was quite impressed, but I felt sad on the inside

I remember I bought some cheese that is famous at local cheese for my family. I remember I bought some famous local cheese for my family.

Reworded to sound more natural

I remember I bought some local cheese that is famous at local for my family. I remember I bought some local cheese that is famous for my family.

We ate ithem all forin a few days. We ate it all in a few days.

I'm guessing that you ate all of the cheese so have worded it for that meaning