It's a pleasure to have you back, @retchison.

Let me share some info about generating Profit and Loss reports showing the previous period in QuickBooks. 

When you customize the report and select Previous Period, it will normally show the first two weeks of the current month and the last two weeks of the previous month. 

If you want the Profit and Loss report to show the same time frame, you can select Previous Year under Columns. Please screenshot below for your reference. 

In case you need further help adding filters to your report in QuickBooks, feel free to review this article: Customize reports. After, you can memorize them if you want the same customized report settings available for future use.

Let me know in the comment section if you have other concerns with managing reports in QuickBooks. I will gladly lend a hand. Have a pleasant day.