Hello everyone
I have an inquiry. If I modeled stress system with MM. unit file and I want to change it to Bar. file is that possible.
I tried to change unit file in configuration file but does't change any ideas?

In configuration file you can change only for new files and for output. Go to "Utilities" tab and use "Change Model Units"

just to clarify...
New models will start with the unit set specified in the configuration file. Whenever you open that file, no matter what the current configuration setting, the model will display those "birth" units.
Output always displays units defined in the configuration file (no matter what the input units).

You can change the input file units, as danb says, through the Utilities ribbon on the Main Menu. Just point to another units file (*.FIL) on your PC.