My app preferences are not updated

The app settings can be changed at any time on the app preferences page.

After you change any value, you must click 'Save' for the new settings to be applied; you can find the button at the top of the page on the right and the bottom also on the right :

At that moment, the new settings are applied.

However, please note that the preferences may be cached for a minute in your browser so, if you had already opened a page with the app widget in your browser, you have to refresh the cache to see the new settings applied. You can do that easily, for example, by pressing CTRL + F5 if you're on a Windows machine or SHIFT + 'Reload button' if you're on a Mac.

You can always clear your browser cache as a last resort, but this should not be normally necessary.

Please check https://en.wikipedia.org/wiki/Wikipedia:Bypass_your_cache for shortcuts for all browsers and instructions on how to clear caches.