What is the difference between importing and don't import? and how to set it back to default?

I downloaded megascan meadows from market place and imported as tutorials say but when Importing in lower right corner of UE it said for example 100 changes made to level (I can’t remember exactly what it said) what do you want to do? Options available “import” and “don’t import”. What is the difference between these two options? And I clicked on don’t ask me again and how to uncheck that option so it asks me every time?