Simply open your History panel.
Then at the top left of the panel, click the menu "Import and Save". And there, the first line you find in that menu is... "Save". It saves all your history.
Simple. Direct. Without any need of a technical knowledge and without any need of an extension.
In the past there was the wonderful extension FEBE, from Chuck Baker which was the best to make backups of everything at once or feature by feature, and automatically (scheduled) as well as manually. But since Firefox 57 Quantum it doesn't work any more, like many other wonderful extensions which were awesome (Add Bookmark Here², CLEO, DownThemAll, FEBE, FireFTP, FlashGot, Location Bar Enhancer, OPIE, Roomy Bookmark Toolbar, Saved Password Editor, Show Parent Folder, TabMix Plus, etc, etc, etc). Conclusion : as many very old Firefox users which were faithful to Firefox from the very first days I have ended up by being definitely fed up and I have eventually dropped Firefox recently. All along these last 6 years the management team of Mozilla has taken the habit to turn the back to the users. That's why Firefox which was a wonderful browser with more than 80% of the netizens throughout the world at the end of the last decade has now fallen to a pitiful 10% of use among the different available browsers.
If instead of Firefox you use Cyberfox or Waterfox or Palemoon you can keep on using >>ALL<< these old awesome extensions that I cited above. But not in the native Firefox. So the best is to use Cyberfox or Waterfox or Palemoon instead of Firefox. You won't be disturbed nor worried... as they all are forks of Firefox in its former way to work BEFORE Quantum.