I would like to create a Statement of Financial Position report that compares current balances with start-of-year balances. How?

I'll share details to help with your question about running reports, acctspayable-stg.

For now, we're unable to create a Balance Sheet report that would compare the current with start-of-year balances. The Balance Sheet Comparison that we have in QuickBooks Online only compares the data from the previous year. 

You'll want to run two standard Balance Sheet reports. Then, customize the dates to the start of the year and the other one that would show the current balances. You can then export them to Excel and merge or combine both reports. Here's an article as a guide: Export Your Reports to Excel from QuickBooks Online.

I would also recommend sending feedback or a feature request about this to our product engineers. Check out this article for more details: How Do I Submit Feedback?.

Additional references when running reports are also provided here:

• Customize Reports in QuickBooks Online 
• Common Custom Reports in QuickBooks Online 

Reply to me or post another question if you need anything else. We'll make sure to offer our help anytime of the day.