Thanks for the reply Akhil. I should provide more details.
I setup my ArcGIS Mobile project on PC running Windows 7. In the Mobile Project Center my scale bar displays as miles, yards, feet depending on the scale. This is the same when I open the mobile project with ArcGIS Mobile on the PC.
I then load the mobile project onto a Trimble Juno SB, it opens and all data layers work fine, except now my scale bar displays metric units (km, meter). Regional Settings on the Juno are set to English (United States), which is the only OS settings I can locate on the Juno that would switch between Metric and Statute (US).