QuickBooks Desktop for Mac uses a different process for backing up data, and requires a different process to restore backups.
When a data file is backed up it creates a disk image (.dmg) file. Each disk image QuickBooks creates when it backs up your data includes a copy of your company file and your Attached Documents Library (if you use and back up attachments).
To Find the location where QuickBooks For Mac might have stored the Back up you can go to QuickBooks > Preferences > Backup.
Note: If the backup is not in the specified folder, navigate to the drive or folder where the backup was saved, or go to Spotlight (the magnifying glass icon at the upper right corner on the menu bar) and search for files with the .dmg extension.
To restore the Company File from the DMG.
To restore your Attached Documents:
To restore qbmb or .mac.qbb non image backup files created in any QuickBooks for Windows versions (QuickBooks for Windows 2013 and 2014 still create a mac.qbb and not a dmg file)