in the yahoo desktop app you can set your lineup for the day, the rest of the week, or all 3 teams and all 3 options work properly.
In the IOS app has the option to set your lineup for the day, rest of the week, and offers a subscription to fantasy + to optimize your lineups and both options work properly.
In the Android app, you have the option to set your lineup for the day (tested with an empty roster spot and does not work), the rest of the week (locked and requires yahoo fantasy + subscription), or all teams for the week(this appears to set all teams arbitrarily). You can no longer set your lineups for a single team for the week any more. i'm not sure if the intention was to have the subscription to allow you to set lineups for all teams at once, however the way it is right now the single day does not work properly, and if you cant set your lineups for a single team for the entire week.

It would be nice to have some consistency between the 3 platforms. I am primarily an android user and the app is almost unusable in it current state when attempting to manage my lineups. I and in 3 leagues and we have almost 20 android users in those leagues and they all have voiced concern over this issue.