You can (and should) make a backup of your databases at any time, simply with File Backup from the main menu:
The databases are written to the QVX_Data\Backup folder in a zip file.
QVX performs this backup automatically every 7 days when you close the app. In Settings-General-Xplorer you can change the interval or turn it off if you set 0 there.
Note: this backup function only backs up databases in their own QVX_Data folder. Databases in external connections are not backed up.
You can back up each database individually. To do this, simply select Backup Db from the database context menu. The database will be copied uncompressed into the QVX_Data\Backup folder and the current date and time will be added to the name. If you travel with Gps-Online function activated, you should make a backup once a day.
OneDrive, DropBox etc are very convenient services to back up on the go. You can set up your OneDrive or DropBox access directly in QVX as connection. Then you can simply drag&drop databases into the cloud folder in the Tree view and they will be copied.
Warning: please never connect the local cloud folder, e.g. User-Name-OneDrive in QVX as a connection. If you insert tables or tracks, routes, waypoints into a database located in this folder, it will most likely break because the cloud driver will start syncing immediately while QVX is inserting data.
There is no function in QVX to restore backups. If necessary, use the Windows Explorer or Mac Finder to copy back the required databases.