You can change the Content Buttons order, as well as their layout. For this, in the Studio, go to Event builder → Content display → Content Buttons
Changing the Content Buttons order
On the right-hand side of each Content Button there's an icon in the shape of three lines and two arrows: click and hold your mouse/pad and slide upward or downward to change the order in which each Content Button is listed.

Changing the Content Buttons "Display mode"
Content Buttons can either be displayed as a List or as Grid.
List display mode

Grid display mode

The Grid mode allows you to add a Background picture for each Content Button. To add a background picture, click on the Edit "pencil" icon right next to the desired Content Button.

Then, under the Design tab, add an image of 600x200px and no larger than 300kb as the Background picture.

The Grid mode is particularly useful when you have a large number of Content Buttons.