How do I change the default language?
There are a few places where you can change the language, each corresponding with a different part of LastPass.
Online Vault and Account Settings: Go to your LastPass Vault > Settings > General > Language
Local Vault and Extension Menu: Go to your LastPass Icon > Preferences > Advanced > Language. Restart the browser.
On Windows, if you run the Windows installer you can also choose your language; to reset it, you can uninstall LastPass (Start Menu > LastPass Uninstall) and then re-run the installer: https://lastpass.com/download.php.