If it helps, for the Duivendrecht trains from Schiphol... Duivendrecht will not be the destination. They usually go through to somewhere like Lelystad or Utrecht (marked 'via Amsterdam Zuid/WTC/RAI', or similar). You can check on the platform for the red signs on the boards saying "this train does NOT go to Amsterdam Central". Duivendrecht is the 3rd stop, and takes about 10-15 minutes.
Duivendrecht is just a little, modern station, on split levels. Easy to change at.