I appreciate your efforts in reaching out here for help.
In QuickBooks Self-Employed, the ability to categorize for both income and expense in one invoice transaction is unavailable. You'll have to enter them separately in QuickBooks to properly account for them.
You'll want to create and use rules to quickly categorize your transactions. Here's how:
Go to Settings and select Rules.
Click Create Rule.
In the Description field, enter the customer or vendor you'll want to create the rule for.
From the Account drop-down, select the account.
From the Type drop-down, select Business, Personal, or Split.
Put a checkmark to the Also apply to past transactions box if you want the rule to apply to transactions you've categorized.