You were using the previous version QV-Mobile 3 already and want to use your existing databases with QVX-Mobile?
There is no build-in feature to import your existing databases, but you can do it manually with iOS Files App.
Open Files App
goto Browse
tap On My Phone
you'll see a list of apps on your phone including QuoVadis Mobile, this is the old app, and QuoVadis X Mobile, this is the new one.
tab on the old app QuoVadis Mobile, then on QVM_Data, then on Dbs and you'll the the list of all your databases.
tap on the menu button (…) in the top right corner and tap Select
now select all Databases you want to copy
* tap on the menu button (…) in the bottom right corner and tap Copy
now go back to Browse and then On My Phone
tab on the new app QuoVadis x Mobile, then on QVM_Data, then on Dbs
long tap in the empty space below the last item and select Paste
You can also copy/paste the whole folder Dbs, even the other folders.