The app on mobile devices will check for changes automatically from the server every 15 minutes. Changes you make via the CMS, can take that long to appear on devices.
Users can force an update, at any time, by clicking the refresh button. It appears at the top of the slide-out navigation menu.
Support can force a DB update when needed, which will merge all of the small delta changes into the master Db. This will make it so that any new users who download the app, see all of the changes made immediately - essentially downloading the most up to date Db.
An XLS upload (even a blank spreadsheet), will have the same effect as above. Merging all delta DB's into the master DB. So for the best outcome, changing content via XLS is recommended. Make sure to always download the data being changed from QP, to ensure that you are always working with the most up to date data and that you have a backup of the data, should any errors be made with the XLS upload.