I discovered that when I add some favorite airfields (whishlist to visit) by using the "add" button on top of the "airfield list" at the airfield tab,
t‌hese airfield are lost after certain time or lost when I log In after I have logged out ...
I‌s this normal?
I‌f so, would it be possible to create a "WhishList" of airfields I want to visit in the future? A list which is saved even when I logged out?
T‌hanks ! 

The airports in the Airports list are the airports used when you create a route and relevant to this route.
‌It is not supposed to hold a list for future use.

You could create a  "Wishlist" route, add the airports you want and then save it.
Each time you open that route you would have the airports that you saved within.