This app ships with sample categories that could be imported separately for expenses and for revenues
Just tap the Add menu button which opens an input dialog.
Tap a list entry and then (depending on your Android version)
either tap on the corresponding menu button at the top of the screen Details
or select the desired action from the pop-up menu
Note: Changing a category affects all assigned expenses or revenues.
Tip:
You could use the note field as a sub-category, e.g. Gas as a sub-category of Auto. With reports you could then calculate per category the shares of its sub-categories.