Lab2.2 Optimizing compound index

Even though i answered this lab correctly based on the concept, I still have a question.
When i create all six indexes on people collection in compass, and try to run these queries, it always uses a index which is different than the correct answer. I hope the compass is picking the optimized & best index for running the query. So this feels very strange to me, can anyone explain this phenomena or I am missing something?

First, Compass is not picking an index. All find and aggregations are performed on the server. So the same indexes will be used what ever you use Compass, mongo shell, or language specific driver.

Second, we cannot really indicate you what is wrong with your index and find if you do not share them with us.

Thanks steevej, the first part of your answer clarifies my question.