The app created by Web AppBuilder is saved as an item in My Content. The item type is Web Mapping Application. Go to My Content and click the item's context menu to view or edit the app.
On the item details page, click the arrow on the Open button and select View Application to start the app.
If the App State check box on the Attributes tab is checked, when you close your browser, the app state, including map extent and layer visibility, is automatically saved. As a result, you will see the same app state the next time you open the app in the same browser.
On the item details page, click the arrow on the Open button and select Edit Application to edit the app in Web AppBuilder. Once you finish editing, save the app.