Problem with MacOS app. I want to delete all local data after update 1.8

I still have a problem with my local MacOS app since update 1.8.
I created a new user on my Mac to try if the problem remains. I doesn’t. Therefore I know it has to do something with my local data related to the user. My plan: Delete all local data, before I backup of course from the web server, then restore. What files do I need to delete so denote things the app is installed for the first time?

Please contact support using the “Contact Support” button accessible from the ? button in the lower right of the app.