Under Design - Smartphone you'll find our homescreen editor - fist tab, Home. Tabs 'Colors and fonts' and 'Graphics' didn't change.
Layouts to choose from are on the top, you can either use that or new, advanced editor, which opens by click on gear in the top right corner. If you open advanced settings and then choose from the layout on the top, all your advanced settings will be lost (a confirmation popup will appear).
To add your own icons, click on field in column Icon and go to My icons - you can upload more than one icon at once.
Icon background for default and pressed state can be set for each icon separately, or, if they’re the same for all icons, you can just upload them to Default icon background.
There are also options to hide icons or text, and change font.
Here you can define the size of the icon grid, layout position, button size, icon margin and scrolling type and direction.
To change the button size, you can use the slider, or just type in the number.
Icon margin defines 'space' between the icons.