Add a Hide/show option for Budget available equal zero
When consumed the total budget of a category the available became to zero. If a significant quantity of these categories are in available equal to zero, you lost the focus of what categories needs to be controlled and lost the knowledge of what budget can be move from one to another category.
I think that can be easily fixed adding a hide or show option for the budget categories that are in zero. With this shorter list of categories you can focus easily.
Particularly this problem is worse in the Mobile App because there the category group cannot expand or contract as the web page do and then the list can create a long scroll difficult to know what is happening.
The option of Hide or Show categories available equal to zero can also be applied over category groups.
I have organized my budget so that all of the categories I could move money from (i.e. my routine/flexible/discretionary categories) are together in two category groups and I keep these at the top of my budget. This makes it easy to quickly see how much money is left in those categories and also where I can take from if I need to move things around a little -- especially on mobile because they are all together at the top of the list.
I have a little lock icon in the name of the other category groups that contain my fixed expenses, true expenses, and savings funds to indicate there is no money here to take from as I budget those to exact amounts each month and rarely need to be looking at them once they are funded. Even though this goes against the priority order, I find it more useful because I know my priorities well enough that when I am funding my budget (2x per month), I know where money needs to go -- my goals help with this as does putting the due date in category names.
It is much more useful to me to have things organized in a way that will make it easier for me to work with throughout the entire month.
Can't help with the mobile app, but the YNAB Toolkit, a 3rd party open-source browser extension, can hide zeros. There are numerous other improvements it adds, and I would not run YNAB without it. (Link is for Chrome, but Firefox is also supported.)
In the mobile app, you can also pin categories to the top of the list. I put my most-used variable spending categories there, like gas/groceries/etc so that they're already immediately visible to check available balances. I like to "cover overspending" on the mobile app because it's so easy - since I usually only move money among those discretionary categories, they show at the top of the list in that move money tool as well.
I put "cover overspending" in quotes because we look to see where the money will come from before making the purchase, but it's easier to enter the transaction, then let YNAB move the exact amount needed for me after the fact.
To pin a category on mobile, tap the category, then details/activity, then the pushpin icon in the top right corner. You can rearrange the order of the pinned categories, and they will still show up in their normal places below.
This is a device specific setting.