Changes in Page Builder are saved even before you save or publish the entire page. If Page Builder hangs before your work is saved or published, it’s usually safe to reload the page in your browser. In addition, you can edit the settings for rows, columns, and modules and then open any other row, column, or module for editing without needing to click Save.
…click Done in the upper right corner and select one of the following:
If you save a draft, be careful about discarding future edits. In Page Builder, changes in the layout are saved as you edit, and the Save draft choice is a way of exiting Page Builder without publishing the changes. If you choose Discard in a future session, you'll lose all changes since you last published the page. Also, the WordPress Revisions feature (see the next section) only works with published changes, not saved drafts. Note that this can happen inadvertently if more than one person is editing the page at the same time. If another person discards edits on a page while you are editing the same page, your changes can be lost.
Here are some things to keep in mind about the way save, publish, and discard work: 1) Be very careful when you choose Discard, because it means you will lose all changes between now and the time you last published, even changes from a previous editing session that weren't published. You'll see a warning to remind you before you discard. 2) An alternative approach is to avoid using Save draft. That way you'll know if you discard your changes that you are only losing the changes from your current editing session. Using Save draft is even riskier when other users have editing capabilities for the page you're editing. 3) Consider publishing at regular intervals. This will create a WordPress revision that you can return to if you want to revert your most recent changes. This is also a good practice because there is no Undo when you're editing in Page Builder. 4) It's a best practice to work on a copy of your site in a staging location rather than editing a live site directly. That way you can publish at interim points without the changes going live, and it's easier to backtrack if something goes terribly wrong.
You can revert to previously published versions of your page using the WordPress Revisions feature.