How do I print a single customer's profile (ie. address, telephone numbers, email adress)?
QuickBooks Online organizes your customer data in the Customers section of the product for easy access and easy transaction creation. I know having a paper copy for your files or for various other reasons is also useful, and I'm happy to go over how you can pull that information from the program.
Your best resource for this situation is going to be a report called the Customer Contact List. You can find it in the Reports tab of the left menu, and it brings up a complete list of your customers with their contact details and other information added to the profile. The report will default to a few specific columns, but by clicking the small gear icon on the report or the Customize button to see all the report customization options, you can add more columns for the information you need.
With those customization options, you can also filter the report to see details for a specific customer so that when you print it, you only have the information you're looking for. Here's how to do that.
Click the Customize button.
Check off the Customer box.
Choose the customer you'd like from the drop-down menu.
Select Run report.
Once you've got it set up the way you'd like, click the Print icon along the same icon line as the small gear I mentioned earlier. You'll also see the option to export or email the report if you so choose.
If you're looking to print something formatted more like the customer profile in QuickBooks Online, that's not currently available. I recommend leaving feedback for our product developers in that case: How do I submit feedback?