How do I add a vendor's invoice for payment in my QuickBooks Online? I use QBO on my desktop and my tablet, and I cannot find it on my Samsung Tablet?

Welcome to the Community, @dhughes-absolute.

Currently, it's unavailable to add vendor invoices or bills using a tablet device.

I suggest adding your vendor's bills by logging in to your QuickBooks Online account through a web browser.

Here's how:
 

1. Sign in to your QuickBooks Online account.
2. Go to Expenses, then Bills
3. Hit Vendor, and select the specific vendor
4. From the Terms ▼ dropdown, select the bill's terms.
5. Enter the Bill date, Due date, and Bill no.
6. Enter the bill details in the Category details section. From the Category dropdown, select the expense account you use to track expense transactions. Then enter a description. Enter the Amount and tax.
7. If you plan to bill a customer for the expense, select the Billable checkbox and enter their name in the Customer field. Learn more about billable expenses.
8. When you're done, select Save and close.
    

I included this article to learn which QuickBooks Online app features are supported on mobile devices: Compare mobile app features.

Moreover, I recognize the convenience of having the feature added to QuickBooks. I suggest sending feedback to our product engineers. Rest assured that your input and ideas are appreciated.

You may also want to check out this page to keep updated on new QuickBooks product updates: Firm of the Future.

For more vendor-related questions, you can always reply to this post. I'm always available to support. Have a great day!