It would be great if the cards shown on activities was shown in the same order as they are stacked on the boards, instead of just sorting them after which board they are on and after that alphabetically.
How the sorting could be, based on the order they are stacked when there's no grouping set on their respective board:
1. Sorting cards first by which board they are on, alphabetically by board name (as it is now).
2. Within each board the ones which are on the rightmost column before the "Done"-column (the cards on the "Done"-column should be shown as they are now) then going left, column by column, until the leftmost column.
3. Within each column the card which is on the top of the stack in this column first, then the second and so on.
By sorting this way activities will be more closely linked to the cards and boards, giving projectmembers a more effective way of getting an overview of the project.