You can customize the options, but your changes last only for the duration of the current session, unless you instruct FeatureCAM to save them.
Automatically save all options... — Select this option to save the current settings when you exit the program. If this option is not selected, the settings for your current session are not saved to the files when you exit.
FeatureCAM uses two .ini files to store your settings:
The ezfm_mfg.ini file contains default values for both inch and metric attributes. For example, there is an entry for zrapid in inches and also an entry for zrapid_mm in mm. In general, the name for the metric attributes is the same as the inch name, with a suffix of _mm.
You can make a backup copy of the .ini files before you save any changes; this way you can revert to the default settings if something goes wrong. Alternatively, you can delete the .ini files; when you restart FeatureCAM, these files are recreated automatically with the default settings.