Version 3.8.3.20986
S‌ince the latest update it is a mess with the downloaded airports.
A‌fter leaving the app and a new start of the mapp all the downloaded airports are deleted and have to be downloaded again.
D‌oes anybody can confirm this bug ?
I‌t worked so fine with the older version.

N‌ice greetings
D‌avid‌

Create Route creates a new route. It is not surprising that any changes you made to your previous route are lost, in fact, that's the whole point.