Hi @Apples24,
Thank you for your prompt reply.
The steps provided above are intended for a browser. You'll need to login to your QuickBooks Online (QBO) company using a computer. Since both platforms sync with each other, any changes made from one will reflect with the other.
See this article for a list of features available on different mobile devices: Compare mobile app features. So you know which device has the features you need.
Tap the Reply button and post a comment below if you have other concerns with sending invoices from your QBO mobile app. I'll take care of them for you.