If QB online backs up our files online, how do I access a backup file? As a new user I seem to have wanted to change an account in one entry and it changed them.

Hello there, Topaz. Let me help you access your backup company in QuickBooks Online (QBO).

If you want to undo unwanted changes to your company file, you can restore the backup of your company file using QBO Advanced. To do that:

1. Go to the Gear icon and select Back up company. If you're prompted to sign in, enter your login credentials and click Authorize to proceed.
2. Find the company you want to restore.
3. From the Action dropdown, click Restore.
4. Select the date you want to restore in the Date field.
5. From the Time dropdown menu, choose the time you want to restore.
6. Enter AGREE in the Ready to restore your backup? section.
7. Click Next. If you see a list of suggested actions, follow them first. Once done, select Refresh to continue.
8. Click Start Restore.

While the Online Back-up & Restore app restores the data, please don't do anything in your company. When finished, you'll see a checkmark in the status. 

More details about backing up and restoring your data are outlined in this link: Back up and restore your QuickBooks Online Advanced Company.

Additionally, feel free to check out this article if you want to have an overview of the different areas of your business, including sales and expenses: Run reports in QuickBooks Online.

Fill me in if you have additional questions about restoring your QBO company. We're always available to assist you further. Keep safe!

@Topaz 

If you are not using QBO Advanced, you can use a 3rd party backup restore app.

https://partnerwithus.rewind.com/quickbooks