Hi there, raleighkim.
Allow me to shed some light on that checkbox for you. When you check the "Transfer" box next to Cards on a customer invoice in QuickBooks Online, it means you're transferring the payment from one bank account to another.
This feature comes in handy when you receive a payment from a customer but want to deposit it into a bank account different from the one specified on the invoice. Selecting the "Transfer" option allows you to allocate the payment to the desired bank account.
It's beneficial if you have multiple bank accounts in QuickBooks Online and need to track where your payments are deposited. Remember to select the appropriate bank account in the "Deposit To" field during the payment recording process.
Additionally, I'll share this article to help you move money from a bank to a credit card account: Transfer funds from a bank to a credit card account.
I hope that clarifies things for you! If you have any more questions about QuickBooks Online, feel free to ask. Have a great day!