Indeed, a Mozilla reset can be the right solution for a lot of typical issues that come up with a browser, like random crashing, freezing, settings that have gone bad, behavior that is not expected, and that is caused by malicious extensions or just a wrong configuration. The resetting feature brings your settings back to the standard ones, but doesn't get rid of your key personal data, such as bookmarks and logins. Once the reset is over, Firefox starts again with the default settings, and you might have to reinstall the extensions or reapply your usual settings.