If the Invoices tab is unavailable on your account, you can activate this feature by going to the marketplace tab and > invoices > activate. Here, you find an article on how to activate the invoicing tool, and here, you can find an article on how to set up the invoicing tools.
Type of invoice: this is the format of the invoice, and you can select between simplified and detailed.
Simplified: Items in invoices will be grouped by category
Detailed: Items in the invoices will be displayed without grouping them.
Invoice default footer: you can add some text that will appear in the footer of your invoices and estimates.Invoice color: you can customize the color of the invoice.
Invoice logo: You can add a logo to your invoice, the recommended logo size is: Width: 150px - Height: 80px
Then do not forget to click on > Save.