Has it changed so can't see all parts of a level?
Haven't used Duolingo for a while but thought would have another go and I used to be able to go back to any part of a level. Now it doesn't show different parts of a level, and all I can see is how to go from the start
they have introduced 'crown levels' which get increasingly more difficult, rather than completing a section and moving on - you can still do that or you can focus on one particular section and step up through the crown level, good if you feel that is a weak area.
I always though Duolingo was good for what it was, now it is even better (and free!)