May I know what is "cash back goes to" in QBO? When I add some deposits there is an option as cash back goes to and there are some drop down options of my bank accounts.

Let me add some information about this, Kaisha,

In QuickBooks Online (QBO), the Cash back goes to field is an account option where you want to deposit cashback amounts. These amounts are credit card rewards that are either paid out in dollars or points. 

You'll want to choose the correct account where you want these deposits or payments specific to transactions shows up by clicking the drop-down arrow. You may also want to create a new account specific to this deposit. You can do this by just clicking the Add new option. I've added a screenshot for reference:

Additionally, QuickBooks provides several reports that gives you different snap shots of your business. Learn how you can customise them to ensure you'll get the right data you need. I've added this article for more details: Customise Reports in QuickBooks Online.

Please feel free to reach back out if you have any other questions. I'll be here to lend a hand.