Can I add “adding time activity” function to the QBO mobile app?

 I appreciate you taking the time to post today, info. 

The function you quoted is not available in the QBO mobile app. I understand that this can make a difference to facilitate your processes. I recommend sending a suggestion to our product engineers, so they can consider adding it in future updates.

1. Click the Gear icon.
2. Choose Feedback,
3. Enter a sentence to describe your suggestion and click Next.

There are some features that are not available in the mobile app, so you might want to consider signing in using a mobile browser. I'm also adding this article for your additional reference: Enter billable time by job in QuickBooks Online.

Let me know if you have other questions in mind. Have a good one!