To preserve changes to DGN file settings — such as working units — between sessions, you must explicitly save the settings.

File > Save Settings saves the settings in the active design file. This option is enabled only if the "Save Settings on Exit" preference is set to off in the Operation category of the Preferences dialog ( File > Settings > User > Preferences ). This allows you to save settings at will, as they are not automatically saved when you exit the file.

Saved settings include settings controlled through settings boxes and the view configuration (the arrangement of views on the screen and the areas of the design plane displayed in the views). However, user preferences, B-spline, plotting, and rendering settings are not saved.