You can customize the way you see and choose categories when recording expenses (also accounts and other fields).
If you want to view your categories in a grid:
Go to Settings>Recording, then tap List style
Tap the grid button (right one)
Each field can have its own list style
When choosing categories, Gem shows your most recent ones and allows typing to search for more. If you prefer to immediately see your list of categories instead:
Go to Settings>Recording, then tap Quick search
Turn off the toggle
Each field can have its own behavior
Customize app menu
You can hide some items from the app's bottom menu if you don't use or like them.
Go to Settings>Appearance
Under Bottom menu, turn off the buttons you want to hide