Hello there, @liz-b-powell.
I'm here to help guide you save your data in QuickBooks Online (QBO).
Once you've cancelled your QBO account, you have the read only access to your file within a year after the cancellation date.
To save a backup of your data, you can run reports and export the reports to Excel.
For additional reference about running and exporting reports, you may check these articles:
On the other hand, to learn more about the things you must know before cancelling your QBO account, you may check this: Things to know before you cancel QuickBooks Online.
If you have any other QuickBooks questions, just add a post/comment below. I'll be always here happy to help you!