HI there, Samm. To mark the invoice as paid in your QuickBooks mobile app, you can click the Record payment option on the More tab when viewing the invoice. 

Please know that if you'll link the payment to a specific bank account, you'll need to wait for the payment to clear out to your bank then that's the time you can record the payment in QuickBooks Solopreneur.

Follow these steps to record the payment:

1. Open your QuickBooks mobile app.
2. Go to the Invoices section.
3. Find and tap the invoice you want to update.
4. On the invoice screen, tap the Record payment option.
5. Enter the payment details, including the amount, date, and payment method.
6. Select the bank account where the funds were deposited.
7. Tap Save or Record.

If you have more concerns related to QuickBooks, don't hesitate to reply. We're here to help you.