How to fix all of my Mobile Deposits have been automatically assigned to a specific and wrong customer and they have been categorized as Uncategorized Income, also wrong?

We appreciate you for reaching out here in the Community, hendrik. Let me help you categorize the transactions to the accurate account and customer in QuickBooks Online (QBO).

Beforehand, please note that QuickBooks depends solely on the data shared by your financial institution. 

If the system doesn't know how to categorize a downloaded transaction, it'll be assigned automatically to the Uncategorized Income. It's a temporary withholding account and can't be used to create bank rules.

When this occurs, we can Undo the categorization. Then, categorize the transaction to the accurate account. To proceed, we can follow the steps below:

1. On the Transactions menu, select Bank transactions.
2. Choose the Categorized tab. Then, tick the categorized transactions. You can select multiple transactions.
3. Under the Action column, click Undo. Then, confirm by pressing Confirm. The selected data reverts to the For review tab.
4. On the For review tab, click the data that needs to be designated to the accurate account.
5. Select the 〇 Categorize section, and choose an account on the Account ▼ dropdown. Then, click the correct customer on the Vendor/Customer ▼ dropdown.
6. Once done, hit Confirm.

Meanwhile, this can be avoided by disabling the Enable suggested categorization. This way, you can manually categorize your data appropriately in the future.

Here's how:

1. On your Bank transactions page, go to the For review tab.
2. Click the mini Gear icon ⚙.
3. Uncheck the Enable suggested categorization.

In addition, I'm adding this article that can help you with the reconciliation process in QBO. Doing so ensures that your data matches your bank and credit card statements: Reconcile an account in QuickBooks Online.

Don't hesitate to reply to this thread if you have more concerns with your categorization in QuickBooks. We're always here to help.