Last week my quick books app log out from my mobile

Welcome to the Community, @devcleaners. This isn't what we want you to experience and I'm here to work with you to sort this out. 

We can do a few troubleshooting steps to see if we can fix this issue through updating. Here's how: 

1. Restart your mobile phone and update it if necessary.
2. Open the QuickBooks app again.
3. Log in to your account and see if it works. 

If this is still an issue, uninstall and reinstall the app. This is to help remove any error messages or glitches that may be standing in the way. Once done, turn your device off and then back on.

Check out this article for additional reference: Troubleshooting Quick-Start Guide for the QuickBooks Online app. 

If the same problem occurs, I'd appreciate it if you can specify if you're iPhone or Android? Any additional information that you can share will help me refine my research and provide you with the right information. 

Here's another article for your future reference: QuickBooks Online access for mobile devices. It helps you learn about what you can do with the app. 

If you have any questions, please let me know. I'm always around to come back and help.