@DivinaMercy_N   RE: I'll share details and steps to help you turn off the automated sales tax and default a custom rate in QuickBooks Online (QBO).

Well, you wrote that you would do that, which is a good start, but then you didn't actually tell us how to do that.

So, how do we "turn off the automated sales tax and default a custom rate"? You know, like QuickBooks Desktop, where you can pick the correct tax item to use based on what is appropriate for the sale?