Hi susan-smartopera,
There are times that you'll have to upload CSV files, like the one you're referring to for banking transactions. QuickBooks Online does have a set of date formats that it supports. I can guide you to the best option for importing your file.
On the off occasion, the date format your bank uses isn't supported by QuickBooks Online; the simplest option would be to open your CSV file and manipulate the data in the file to match a date format QuickBooks supports.
You can also submit feedback and let our product development team know that having the additional date format available is requested. Click the Gear Icon. Select Feedback. Fill in your ideas and click submit feedback. When our terrific product development team is deciding on future updates, they look at the feedback to see what people want.
Reach out again when you need assistance. Take Care.
