The history widget is a really cool feature, but I think there are a couple things you can improve to make it even better.
Right now user needs to select a category from the dropdown, which is an alphabetically sorted list of all categories the user has. I guess it would make sense to show only those categories user was spending in, and order them based on the spend amount. Second thing you can do is show the carousel of categroies labels instead of a dropdown. This would look like a merchants list in a ‘What did I spend’ widget.
So instead of selecting and viewing each category separately, user will be able to really quickly flick through all categories.