We can take some basic troubleshooting steps to fix the issues you're facing with your QuickBooks mobile app.
Your app can have too much saved data (cache) that's causing issues. Here's how you can refresh your app and phone settings:
In the QuickBooks Online app:
Android: From More Options⋮, select Settings and tap Refresh Data. Then, choose Yes.
iOS: From the Menu ☰, select Help & Feedback and tap Refresh Data. Then, tap Refresh.
In your device Settings:
iOS: Open Settings, go to General then iPhone Storage. Find an app using a lot of space. To free up space without deleting app data, choose Offload App.
If the issue still occurs after refreshing, uninstalling and then reinstalling the app can help. Here’s how:
Tap and hold QuickBooks Online on your phone.
Drag the app to the Uninstall section or use the uninstall option that appears.