The new Design Layout area allows you to change what columns are visible and where they are located in a given report.
Access
To access this menu, navigate to the desired menu and click on "Layout" at the top bar.
Selecting Columns
The design layout menu is split into two sections.
The section on the left includes a list of all potential columns to be displayed on the report. What is listed here will vary from report to report. Checking a column will include it in the report and add it to the right column of the design layout screen.
The section on the right allows you to organise the order that the columns appear, with the topmost items being leftmost on the report. You can click on the grey dots to the left of each column name to drag up or down. Releasing the mouse will leave the column where you moved it to.
Click apply to apply changes.
Saving
To ensure these changes remain on the report, you'll need to click save and select "Make this report the default".