Is there a way to report on transactions posted on a specific day

pick the report that shows the transactions you are interested in, then change the date range to the day you are interested in

ie report on a P&L

change the date to yesterday and the report will show one days P&L

or

report on purchases and do the same thing

Hello there, @accounts55. 

Thanks for posting your question here in the Community. Allow me to share some information about running a transaction report on a specific day. 

You can run a Transaction List by Date report and customize the date, and here's how: 

1. Hover over the Reports tab and click on Reports. 
2. In the Find report by name search box, enter Transaction List by Date. 
3. At the top of the report, select the specific date. 
4. Choose Run report. 

For additional information about customizing reports, you can check out this article: Customize reports in QuickBooks Online. 

If you have any more questions or concerns, please don't hesitate to comment below. I'm always here to help. Take care!