Hello there, @Karin R.
QuickBooks Online (QBO) won't function without connecting it to the internet, and I recognised the convenience of using it offline.
Moreover, I'll also share this link where you can search for articles that can serve as your reference to guide you manage your QBO account: QuickBooks Online Help Articles.
Feel free to leave a reply if you have additional QuickBooks-related queries. The Community team always has your back. Have a good one.
