Saving Standalone Models
To save your current model that you have been editing, select File | Save to save it back into the same file location as it was opened from. This will overwrite the earlier version of the model irrecoverably.
Alternatively you can save the model to a different file or folder by selecting File | Save As … and navigating to a new folder and filename in the dialog that appears. Note that if you do this, the new name and folder selected will become the default save location used by subsequent File | Save menu selections.