A. Force close the app and restart it. On your iPhone, swipe up from the bottom of the screen (or double-click the Home button) to view open apps, then swipe up on the Jack in the Box app to close it. Reopen the app to see if the issue is resolved.
B. Clear the app's cache. Go to Settings > General > iPhone Storage, find Jack in the Box, and select 'Offload App'. This will free up storage and may help with performance issues.