Hello aviomechcorp,
Great question! I'm here to help and can explain your options for QuickBooks Self-Employed and QuickBooks Online.
Fiat Lux has pointed out a great article that lets you know how to download bank transactions from QuickBooks Self-Employed and then import them into QuickBooks Online. I appreciate the call out about the link for Step 1 not working, and it's something I've reported. I've also reported that the wording for that article would benefit from being changed as there isn't currently a way to import mileage data into QuickBooks Online. Using the steps in the article given would upload everything to your bank feed, which doesn't translate to the mileage tab.
That being said, re-entering your trips into QuickBooks Online is the way to go to make sure you have all the appropriate data in your account. The interface works very much like it does in QuickBooks Self-Employed, so I'm sure you'll be able to zip through it.
Please let me know if you have any further questions!
