Let me guide you on how you can match the deposit to the correct invoice, CaitPHG.

Yes, you're correct. You can unmatch the mobile check deposit and match it to the correct invoice. But before doing, so you'll have to manually edit the reconciled transaction first. Please take note the screenshot I've provided is my QBO sample account in the US version but will work just the same as in the International version:

To manually edit the transactions, you can follow the steps below:

1. Click Accounting from the left menu, then select Chart of Accounts.
2. Find the bank account from the list and click View register.
3. Click the Check column until it shows blank or cleared. 
   
   
4. Click Save.

Once done, you can now unmatch the transaction, then match it to the correct invoice. Then, change the status again of the deposit to reconciled (R)

Also, you'll also have to consider and take note of the specific invoice that was previously matched. Since you'll be unmatching the deposit and applying it to the correct invoice, the previous invoice will now be left open and will show as unpaid in status. 

Furthermore, QuickBooks automatically generates a reconciliation report for each session. You'll want to view, export, or print the report for your reference. I've added this article for more details: How Do I View, Print, or Export A Reconciliation Report?

Keep me posted if you have any questions about reconciliation or matching your transaction. I'll be right here to help.