You can find options for the project-wide design and appearance of numbered bar regions on the Bar Repeats page in Engraving Options.
The options in the Numbered Bar Regions section allow you to change the default staff-relative placement, alignment, frequency, and appearance of numbered bar region counts, including ranges on the first bar in each region and counts on the last bar in each system. You can also change the minimum number of bars required to show ranges.
The options are accompanied by diagrams to help you visualize how they affect the appearance of your music.