Nisus Writer Pro 3.0.2 is not obeying the date format set in System Preferences in Mojave 10.14.5.
Instead of 07/04/19 it shows 7/4/19.
When I choose either of these
Insert > Date and Time > Custom Date and Time…
Insert > Date and Time > Configure Date & Time Formats…
the System Preferences dialog for Date and Time opens. No matter how I set the preference there, Nisus Writer does its own thing.
While I am at it, the instructions are outdated in the dialog for that first menu item above. It reads
Well, these buttons (including the “Configure” button) no longer exist in Mojave and High Sierra. The names have changed. There is an Advanced… button, but no “Customize” button, for example.…which you can customize by clicking the ”Configure” button below. Once there, click the “Formats” tab and then either of the “Customize” buttons.