How do I get the latest version?
Once installed, there are two ways to getting the latest version. You can always reinstall the program again as mentioned in Installation Problems. The installer can optionally do an update instead of a full install so you don't lose your preference settings. You don't have to remove the old version before installing. The other possibility to get the latest release is simply by using the Sync Release feature.
How do I know what new features are added?
After you have updated your file to the latest version, the file Changelog.txt in your root installation directory, usually at C:\Program Files\LTC\LTspiceXVII\Changelog.txt, has a detailed program revision list.
Can I go back to the old version after I execute the Sync Release command?
No. All symbols, models, and programs are updated with the current version. The component databases, standard.*, will be merged with the new ones automatically. If you added new inductors or capacitors, your devices will be preserved and merged with the new ones from the update.