When you make changes to a document and save it or upload it to Sketch Cloud, it will automatically appear as a new version in the Activity sidebar on Sketch Cloud.
You can also see versions for specific Artboards (if they’ve changed) in the Artboard view.
You can click on any version in the sidebar to view an older version. When you’re viewing an older version, you can click the See Latest Version button in the top-right to go straight to the latest version.
You can click Download Document to download the version of the document you’re currently viewing, even if that’s an older version. You can rollback to an earlier version by downloading and saving or re-uploading it to Cloud.