Congrats on your first post in the Community. Your invoices are an important part of you getting paid by your clients. Rest assured, I'll be happy to steer you along the right path so the income account in question appears when creating an invoice.
To get started, it's important to make sure the income account exists. You can check this by clicking on the Accounting > Chart of Accounts menu. If the account doesn't show up on the list for you Chart of Accounts, I suggest adding it using the steps provided in this article here. If the account exists on the list and it's still not showing up as an option when invoicing, I suggest clearing cache and cookies on your browser. Clearing cache and cookies is a great way to clean your browser allowing it to work more efficiently. Here's an article that shows you how to do that: How to clear cache and cookies. If this doesn't work, I suggest using a private/incognito window to see if that works instead. In case this issue persists, I encourage you to contact our support team so they can assist you further with this. Here are our contact details:
Schedule a Callback or start a Chat: click(?) in the upper right in QuickBooks Online > enter "Contact support" > choose Contact Us > provide a brief summary > select Let's Talk > choose Get a callbackor Start a Chat.