The Toggle Master Categories setting offers three variations for opening and closing your Category Groups. [Four variations if you count “Off”.]
Enable Category Solo Mode adds a little checkbox and the text “Solo Mode” to the budget menu bar. Checking that box affects the behavior of the category groups when you open them.
Typically, expanding one category group has no impact the rest of the category groups. Some might be open, some might be closed. But with Solo Mode checked, only one category group can be open at once. If you expand a new group, any currently open group will be closed.
Enable Toggle All Categories adds a little vertical double-ended arrow icon to the toolbar. Clicking on that icon allows you to quickly collapse or expand (open or close) all of the master category groups at the same time. Click once to close all category groups, click again to expand them all.
Enable both adds both the up/down open/close arrow icon and the Solo Mode checkbox to the Budget menu bar. This allow you to quickly access both Category Group behaviors depending on the situation.
If the Solo Mode box is checked, the Toggle arrow does not work (you can’t open all categories). If you generally prefer to work in Solo Mode but then temporarily need to more than one group open, simply uncheck the Solo Mode box and click on the Toggle arrow.
The gif below demonstrates both the Toggle All and the Solo Mode options in action.
This setting is definitely in my Top 10 of best, most useful Toolkit settings! It’s a wonder this functionality hasn’t made its way into YNAB’s core code yet.