When I add a new Product from iPhone, Product type is automatically assigned as "Service". How to ensure all new products added via iPhone be assigned"Inventory" type?

I'm here to ensure you're able to assign your new products as "Inventory" types using the QuickBooks Online (QBO) mobile app, @thi.ngo. 

You're on the right track in adding a new product to the app from your iPhone. Here are a few possible reasons the program automatically assigned it as "Service": 

• The app's OS version isn't supported. 
• The stored app data is full.

First, let's make sure the app's OS version is 9.3 or later to get the latest updates. I'd suggest going to Settings and select General. Then, tap Software Update.
 

Second, let's clear the stored app data so it'll function efficiently. I'll guide you how. 

1. Open the QBO mobile app. 
2. Go to the Menu (Three Horizontal Lines) icon. 
3. Select Help & Feedback.
4. Choose Refresh Data.
5. Click Refresh.

Also, you can remove the cached data in your device settings. You'll have to select Setting General iPhone Storage and choose QuickBooks Online. Then, tap Offload App. For more details, see the third step through this article: Troubleshooting Quick-Start Guide For The QBO App. This link is specific to the UK region, but it also applies to your country. 

However, if the issue persists, I recommend uninstalling and reinstalling the mobile app. It helps boost the app's performance since it'll have a clean slate. This way, you'll be able to assign your new items to the "Inventory" types. 

Furthermore, I'd suggest using this chart through this article: Compare Mobile App Features. Just go to the iPhone column to learn more about the other features available in this app, such as creating customers. 

You can count me in if there's anything else you need. Keep safe always, @thi.ngo.