Thank you everyone for the responses. However, I am still unable to merge these two accounts. There seem to be two problems (and it's odd, btw, that you can't see the screenshot, which seems to defeat the purposes of that feature...still).

When I look at the Chart Of Accounts in QBO, find the Cash account, and under Actions click Edit I do not get the screen you show. Instead, I get an Edit Category screen, which looks different and pops to the right. Since I don't see how to actually insert an image into this dialogue, I'll describe it:

It pops out to the right with the title of Edit Category.

The three fields in this panel are Category Name*, Account type*, and Description. There is also an option to "Move category under* Bank & credit cards.

When I change the Category name to Novo Checking, leave the Account type at Checking, and change the Description to be Primary Checking Account, which are the same values as the Novo account, I get the following red error at the top:

You can't merge any account with Novo Checking because it is reserved for a default account.

So either I am doing something wrong, that causes me to get to a different screen somehow (I'm just doing it from the Chart of Accounts), or something is misconfigured, or something else is wrong. The Novo account is connected to the bank which I thought might be the problem, but the error suggests otherwise. I do not know how to get the screen that you show in your answers (I am in QBO Simple Start).

Does any of that help? Do I need to move these categories under Banks & credit cards? Could that be the problem? My most recent payroll did put the entries in the right (Novo) account this time, so it is just this stray handful that went into this separate Cash account, and I just need them combined but can't recreate them because of the link to Payroll (unless there is some fancy way to do that behind the scenes).

Thank you for your help!