Don't worry to much about it. You will feel stupid in whatever society you are new to. I am a Norwegian and I lived a bit over a year in the US.

I think people frequently thought I was real stupid, because I simply did not know how a lot of things worked in the US.

This was about 20 years ago so things may have changed, but I remember how everybody thought I was stupid for trying to pay the pizza delivery guy with a credit card. Of course in Norway that is the normal way to do it. The pizza guy has a portable payment terminal.

Or they would ask me in the store if I found everything okay. I didn't realize at the time that it was a stock phrase. I wondered if they had observed me having some problems I had struggled with.

Or when ordering a burger they asked if I wanted Lays or Ruffles. That sounded like completely alien words I had never heard before. I didn't realize they were basically brand names for potato chips.

Even little kids frequently thought I was a bit thick in the scull due to all the questions I asked about the most mundane things.

In every culture there are things people know a lot about, which you may know hardly anything about. If you come to Norway, you may feel like an idiot when dealign with winter conditions because Norwegians tend to know a lot about that.

For me in the US it was things like fast food culture, consumer culture and medication. Americans know a crazy amount about this. They know tons of food chains and what they sell and what they like. As a foreigner you are confused. Americans will also frequently discuss all sorts of consumer products and demonstrate huge knowledge about every sort of brand. I don't think we Europeans simple shop as much or think that much about buying stuff as Americans. So we don't know as much about stuff.

For medication there is a huge difference. Americans know a ton about pills. They have so many varieties of painkills and can go on at length about what painkiller to use for what. I think most Europeans are pretty clueless about stuff like this. Health care is generally not for-profit so there is not such a commercial aparatus to push all sorts of pill brands with different abilities. We know maybe one brand, which we tend to stick to.

But yeah as soon as you talk about society, geography, culture and stuff like that it is as if Americans have lost half their brain power. I must say it can be shocking how ignorant Americans are about stuff like that. In the crowd I hung out with the most in the US, none of them could even get right the population of the US. For some reason I got tired of them always going "Do you know how huge America is!" all the time. So I asked them "Do you actually know how many people live in the US?"

They would tell me stuff like 1 billion. Just way way off. It is one thing to not know a capital in Europe. Quite another thing to have no clue how many people live in your own country. Yet these guys could give me every possible deal about how much pulling power different pickup trucks had.

So my conclusion is that it is not that Americans are ignorant per say but that Europeans and Americans just know very different kinds of stuff. It is however puzzling that a country made up of immigrants knows so shockingly little about the rest of the world. I can meet people from China who seem to know more about Europe than Americans. That is just weird.