Can the printed font size on the profit and Loss by month report be increased when creating as part of a custom management report?

It's my priority to help you make sure you can see the font when printing a custom management report in QuickBooks, @chris c1.

When printing a report in QuickBooks Online, click the Fit to page button. This way, you'll have better visibility of its fonts.

Let me show you how:

1. Go to the Reports menu.
2. Choose the Management reports tab.
3. Select the report you need. 
4. On the Print Preview page, click the Fit to page button. 
   
   

If the fonts are still small, I'd suggest exporting the report to Excel. From there, you'll be able to increase the size before printing.

For more details about printing reports, please see this article: Overview of your Basic Reports.

Additionally, I've also added these articles that'll help you manage your reports in QuickBooks Online.

• Customize reports in QuickBooks Online
• Memorize reports in QuickBooks Online

Don't hesitate to comment below if you have other questions about generating and printing statements. I'm always here to help. Stay positive always!