When the sim first came out, it would save your filter preferences in the map. It doesn't do that now. But you can change the defaults if you're comfortable with some minor edits in xml. Look in the Official folder and find the fs-base\worldmap folder. There's a file there called WorldmapFilters.xml that holds the defaults. I always have to edit this after every update, but only once. I turn off the POI's, Fauna, and Cities, then turn on the navaids. The entries are mostly in order as they appear in-sim, so scroll down a bit. Here's a screenshot of where to edit: