Description & Suggested Solutions
If the Units Management has units turned off ( Edit-->Preferences-->Units), then these voxels are arbitrarily sized.
Turning Spatial Units on in Units Management will rescale all loaded data to the working units.
These units are also set in the Units Management, but can usually only be adjusted when no data have yet been loaded.
If the voxel size is unknown upon loading date, you can request Amira-Avizo to prompt with a crop editor to adjust the voxel or bounding box size relative to the working units.
Alternatively, you can load the data and then adjust the size using the crop editor.