You get the FML Settings window by choosing Settings->FML from the menu bar. This window is where you can set the default number to be used for the next FML field that you create. (You have the option to create a new FML field from the Add Element window.)
Edit the Next Field Number field to indicate the starting number you want the Contract Repository to use for FML field number. This number will automatically increment as you add elements with FML fields.
When you have filled in the field, click OK to save your changes and close the window. (Or click Cancel to close the window without saving your changes).
Setting the Default Next FML Field Number, Selecting an FML Field Name