Once you are done editing your page make sure to save your changes by clicking the Save icon on the left side of the panel.
We added random save messages to celebrate your effort creating your website. You can customize those save messages via the bricks/builder/save_messages filter.
Autosave every 60 seconds is enabled by default. You can set your own autosave interval or disable autosave under: Settings > Global Settings > Builder
Publishing A Page
When working on an unpublished page (draft) you can save your draft. Once it is ready for publishing click the Publish icon on the left side of the panel.